Disallowed html tags in help docs

[isra-fel]

Description

In some cases, we will generate help documents like this:

  - `[GalleryApplicationVersionName <String>]`: The name of the gallery Application Version to be created. Needs to follow semantic version name pattern: The allowed characters are digit and period. Digits must be within the range of a 32-bit integer. Format: <MajorVersion>.<MinorVersion>.<Patch>

### -Id
Role Definition Unique Id(Format is <databaseName>.<roleName>).

The <MajorVersion>, <MinorVersion>, <Patch>, <databaseName>, <roleName> are placeholders. But they are recognized as HTML tags (because of the <>). So the build of docs is affected.

Possible solution

We can use a tool like https://www.npmjs.com/package/sanitize-markdown (not verified) and define an allowed list of HTML tags. When it detects any invalid HTML tag, we transforms it to another safe format.

Possible formats:

<Example> -> {Example}
<Example> -> `<Example>`

[BethanyZhou]

Close as tracking by #832
Angle brackets may be included in the interface information of notes section or parameter and command description.

• Interface information in notes section will be removed in v4 if PR#Remove complex interface information from help markdown #1164 merged, tracking this issue by Notes need be removed now #832
• angle brackets in parameter and command description are escaped already as <Example> ->\<Example>\
  See

  autorest.powershell/powershell/resources/psruntime/BuildTime/Models/PsHelpMarkdownOutputs.cs

  Lines 174 to 179 in a638a03

  	public static string ToDescriptionFormat(this string text, bool escapeAngleBrackets = true)
  	{
  	var description = text?.ReplaceBrWithNewline();
  	description = escapeAngleBrackets ? description?.EscapeAngleBrackets() : description;
  	return description?.ReplaceSentenceEndWithNewline().Trim();
  	}