This PR updates some links pointing to nowhere. The folder for most of the documentation files has been renamed from Documentation to docs and there are some links that were not updated. This PR fixes some of them.

Customer Impact

• When opening a feature request, this link is in the issue template: Read https://github.com/dotnet/winforms/blob/master/Documentation/issue-guide.md, which points to 404.
  • When fixing this, the user will more likely find and read the issue guide.

Regression?

• No

Risk

• Some external documentation generators or script might map Documentation to a valid path. This would break in that case.

Test methodology

• Ctrl+F Documentation and check if its affected

Microsoft Reviewers: Open in CodeFlow