Manually fix additional markdownlint problems

- heading levels aren't continuous MD001
- code fences need a language MD040
- table has the wrong number of cells MD056

Author: lornajane

versions/3.0.4.md

@@ -1,6 +1,6 @@
 # OpenAPI Specification
 
-#### Version 3.0.4
+## Version 3.0.4
 
 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [BCP 14](https://tools.ietf.org/html/bcp14) [RFC2119](https://tools.ietf.org/html/rfc2119) [RFC8174](https://tools.ietf.org/html/rfc8174) when, and only when, they appear in all capitals, as shown here.
 
@@ -71,30 +71,30 @@ For extension registries and other specifications published by the OpenAPI Initi
 
 ## Definitions
 
-##### <a name="oasDocument"></a>OpenAPI Description
+### <a name="oasDocument"></a>OpenAPI Description
 
 An OpenAPI Description (OAD) formally describes the surface of an API and its semantics. It is composed of an [entry document](#documentStructure) and any/all of its referenced documents. An OAD uses and conforms to the OpenAPI Specification.
 
-##### <a name="definitionsSchema"></a>Schema
+### <a name="definitionsSchema"></a>Schema
 
 A "schema" is a formal description of syntax and structure.
 This document serves as the [schema](#schema) for the OpenAPI Specification format; a non-authoritative JSON Schema based on this document is also provided on [spec.openapis.org](https://spec.openapis.org) for informational purposes.
 This specification also _uses_ schemas in the form of the [Schema Object](#schemaObject).
 
-##### <a name="pathTemplating"></a>Path Templating
+### <a name="pathTemplating"></a>Path Templating
 
 Path templating refers to the usage of template expressions, delimited by curly braces (`{}`), to mark a section of a URL path as replaceable using path parameters.
 
 Each template expression in the path MUST correspond to a path parameter that is included in the [Path Item](#path-item-object) itself and/or in each of the Path Item's [Operations](#operation-object).
 
-##### <a name="mediaTypes"></a>Media Types
+### <a name="mediaTypes"></a>Media Types
 
 Media type definitions are spread across several resources.
 The media type definitions SHOULD be in compliance with [RFC6838](https://tools.ietf.org/html/rfc6838).
 
 Some examples of possible media type definitions:
 
-```
+```text
   text/plain; charset=utf-8
   application/json
   application/vnd.github+json
@@ -107,17 +107,17 @@ Some examples of possible media type definitions:
   application/vnd.github.v3.patch
 ```
 
-##### <a name="httpCodes"></a>HTTP Status Codes
+### <a name="httpCodes"></a>HTTP Status Codes
 
 The HTTP Status Codes are used to indicate the status of the executed operation.
 Status codes SHOULD be selected from the available status codes registered in the [IANA Status Code Registry](https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml).
 
-##### <a name="httpAndCaseSensitivity"></a>HTTP and Case Sensitivity
+### <a name="httpAndCaseSensitivity"></a>HTTP and Case Sensitivity
 
 As most field names and values in the OpenAPI Specification are case-sensitive, this document endeavors to call out any case-insensitive names and values.
 However, the case sensitivity of field names and values that map directly to HTTP concepts follow the case sensitivity rules of HTTP, even if this document does not make a note of every concept.
 
-##### <a name="undefinedAndImplementationDefinedBehavior"></a>Undefined and Implementation-Defined Behavior
+### <a name="undefinedAndImplementationDefinedBehavior"></a>Undefined and Implementation-Defined Behavior
 
 This specification deems certain situations to have either _undefined_ or _implementation-defined_ behavior.
 
@@ -562,7 +562,7 @@ All the fixed fields declared above are objects that MUST use keys that match th
 
 Field Name Examples:
 
-```
+```text
 User
 User_1
 User_Name
@@ -761,21 +761,21 @@ This object MAY be extended with [Specification Extensions](#specificationExtens
 
 Assuming the following paths, the concrete definition, `/pets/mine`, will be matched first if used:
 
-```
+```text
   /pets/{petId}
   /pets/mine
 ```
 
 The following paths are considered identical and invalid:
 
-```
+```text
   /pets/{petId}
   /pets/{name}
 ```
 
 The following may lead to ambiguous resolution:
 
-```
+```text
   /{entity}/me
   /books/{id}
 ```
@@ -1175,7 +1175,7 @@ See [Appendix E](#percentEncodingAndFormMediaTypes) for a discussion of percent-
 
 Assume a parameter named `color` has one of the following values:
 
-```
+```text
    string -> "blue"
    array -> ["blue","black","brown"]
    object -> { "R": 100, "G": 200, "B": 150 }
@@ -2487,10 +2487,10 @@ The table below provides examples of runtime expressions and examples of their u
 | Source Location       | example expression         | notes                                                                                                                                               |
 | --------------------- | :------------------------- | :-------------------------------------------------------------------------------------------------------------------------------------------------- |
 | HTTP Method           | `$method`                  | The allowable values for the `$method` will be those for the HTTP operation.                                                                        |
-| Requested media type  | `$request.header.accept`   |
+| Requested media type  | `$request.header.accept`   | |
 | Request parameter     | `$request.path.id`         | Request parameters MUST be declared in the `parameters` section of the parent operation or they cannot be evaluated. This includes request headers. |
 | Request body property | `$request.body#/user/uuid` | In operations which accept payloads, references may be made to portions of the `requestBody` or the entire body.                                    |
-| Request URL           | `$url`                     |
+| Request URL           | `$url`                     ||
 | Response value        | `$response.body#/status`   | In operations which return payloads, references may be made to portions of the response body or the entire body.                                    |
 | Response header       | `$response.header.Server`  | Single header values only are available                                                                                                             |