Add missing comparsion operators, BNF grammar fixes, markdown formatting

[glenn-slayden]

PR Summary

1. The BNF grammar is totally broken. This moves forward with a few fixes.
2. Many of the comparison operators were missing
3. Added a few missingSyntax: sections

Please consider this PR on an 'as-is' basis; I believe the changes are a positive contribution which you can use or modify any way you like without my further participation.

PR Checklist

• Descriptive Title: This PR's title is a synopsis of the changes it proposes.
• Summary: This PR's summary describes the scope and intent of the change.
• Contributor's Guide: I have read the contributors guide.
• Style: This PR adheres to the style guide.

[github-actions]

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[learn-build-service-prod]

Learn Build status updates of commit 7be4eb5:

✅ Validation status: passed

File	Status	Preview URL	Details
reference/docs-conceptual/lang-spec/chapter-02.md	✅Succeeded	View (>=powershell-5.1)
reference/docs-conceptual/lang-spec/chapter-07.md	✅Succeeded	View (>=powershell-5.1)

For more details, please refer to the build report.

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[glenn-slayden]

Hey Sean,

I know I said I "wasn't going to come back..." but WOW you worked hard! on that little project. I know how long it must have taken you -- because I was paining over the few changes I did try to make.

I felt like it can be hard to know how far to push further on into an uncertain task that, to me, seemed doomed to fail... but you sure showed me... Great work!

Glenn

[sdwheeler]

I felt like it can be hard to know how far to push further on into an uncertain task that, to me, seemed doomed to fail... but you sure showed me... Great work!

Thanks. I saw what you were trying to do. There were issues with some of the changes, but you were heading in the right direction.

I usually don't take updates to the Language Reference because it was published here from the original source Word document as historical information. However, there is value and fixing some of the flaws from the original document.