Added docs on how to hide a webpart from the modern toolbox (SharePoint#1889)

Author: wobba

docs/spfx/web-parts/basics/hide-web-part-from-toolbox.md

@@ -0,0 +1,46 @@
+---
+title: Hide a web part from the toolbox
+description: How to hide a web part from showing up in the web part toolbox on a modern page
+ms.date: 05/23/2018
+ms.prod: sharepoint
+---
+
+# Hide a web parts from the toolbox
+
+For scenarios where you automatically instantiate a custom web part on a modern page, you might want the web part not to be manually available for end-users. This could for example be a status web part on a home page.
+
+## Configure hiding the web part from the toolbox
+
+By default a SharePoint Framework client-side web part will be displayed in the web part toolbox when a user edit a page. To allow hiding the web part from the toolbox you add set the `hiddenFromToolbox` property to `true` in the web part manifest.
+
+```json
+{
+  "$schema": "https://dev.office.com/json-schemas/spfx/client-side-web-part-manifest.schema.json",
+  "id": "34f6d7f2-262f-460a-8b65-152d784127cb",
+  "alias": "HelloWorldWebPart",
+  "componentType": "WebPart",
+
+  // The "*" signifies that the version should be taken from the package.json
+  "version": "*",
+  "manifestVersion": 2,
+
+  // If true, the component can only be installed on sites where Custom Script is allowed.
+  // Components that allow authors to embed arbitrary script code should set this to true.
+  // https://support.office.com/en-us/article/Turn-scripting-capabilities-on-or-off-1f2c515f-5d7e-448a-9fd7-835da935584f
+  "requiresCustomScript": false,
+  "hiddenFromToolbox": true,
+
+  "preconfiguredEntries": [{
+    "groupId": "5c03119e-3074-46fd-976b-c60198311f70", // Other
+    "group": { "default": "Other" },
+    "title": { "default": "HelloWorld" },
+    "description": { "default": "HelloWorld description" },
+    "officeFabricIconFontName": "Page",
+    "properties": {
+      "description": "HelloWorld"
+    }
+  }]
+}
+```
+
+With the `hiddenFromToolbox` setting enabled, when you edit a page, the web part will not be listed in the toolbox.

docs/toc.yml

@@ -42,6 +42,8 @@
         href: spfx/web-parts/basics/configure-web-part-icon.md         
       - name: Using full-width column
         href: spfx/web-parts/basics/use-web-parts-full-width-column.md        
+      - name: Hide from the toolbox
+        href: spfx/web-parts/basics/hide-web-part-from-toolbox.md        
       - name: Preconfigure web parts
         href: spfx/web-parts/guidance/simplify-adding-web-parts-with-preconfigured-entries.md
       - name: Validate properties