Improve Consistency and Readability of about_Quoting_Rules

[michaeltlombardi]

Prerequisites

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• Search the existing issues.
• I am reporting the documentation problem for version of PowerShell I am using.

Version

5.1, 7.0, 7.1, 7.2, 7.3 (preview)

Link to affected document

https://github.com/MicrosoftDocs/PowerShell-Docs/blob/staging/reference/7.3/Microsoft.PowerShell.Core/About/about_Quoting_Rules.md

Description of the documentation error

As identified by @Hrxn in #8764, the Single-quoted strings section specifies single-quotation marks instead of the standard/correct single quotation marks, which also doesn't mirror the usage of double quotation marks earlier in the document. Additionally, in the same section the document says interpreted as literals when it should more clearly state interpreted as string literals.

Suggested fix

Update the about_Quoting_Rules document to consistently refer to quotation marks and be explicit about interpretation as string literals.