[Format] Suggested edits from Liz Lynch

* Replace "a OAS" with "an OAS"
* Remove extra text from array description
* Hyperlink to YAML Failsafe schema ruleset

Signed-off-by: Rob Dolin <[email protected]>

Author: RobDolinMS

versions/3.0.md

@@ -109,10 +109,10 @@ The HTTP Status Codes are used to indicate the status of the executed operation.
 
 ### Format
 
-The files describing the RESTful API in accordance with the OpenAPI Specification are represented as JSON objects and conform to the JSON standards.
-YAML, being a superset of JSON, can be used as well to represent a OAS (OpenAPI Specification) file. 
+The files describing the RESTful API in accordance with this specification are represented as JSON objects and conform to the JSON standards.
+YAML, being a superset of JSON, can be used as well to represent an OAS file. 
 
-For example, if a field is said to have an array value, the JSON array representation will be used:
+For example, if a field has an array value, the JSON array representation will be used:
 
 ```json
 {
@@ -131,7 +131,7 @@ Patterned fields can have multiple occurrences as long as each has a unique name
 In order to preserve the ability to round-trip between YAML and JSON formats, YAML version [1.2](http://www.yaml.org/spec/1.2/spec.html) is recommended along with some additional constraints:
 
 - Tags MUST be limited to those allowed by the [JSON Schema ruleset](http://www.yaml.org/spec/1.2/spec.html#id2803231)
-- Keys used in YAML maps MUST be limited to a scalar string, as defined by the YAML Failsafe schema ruleset
+- Keys used in YAML maps MUST be limited to a scalar string, as defined by the [YAML Failsafe schema ruleset](http://yaml.org/spec/1.2/spec.html#id2802346)
 
 ### File Structure