Add section for Visual Studio

What does this MR do and why?

This adds a section to the Code Suggestions doc for troubleshooting our Visual Studio extension.

When this is merged, the README of https://gitlab.com/gitlab-org/editor-extensions/gitlab-visual-studio-extension will be updated to link to this page.

This change relates to Set up /docs (gitlab-org/editor-extensions/gitlab-visual-studio-extension#36 - closed) • rossfuhrman • 16.2

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