[DOC] Undocument vendored everything

[nobu]

What was the end-user or developer problem that led to this PR?

Should be nothing.

What is your fix for the problem, implemented in this PR?

"lib/rubygems/vendor/*" directories have the same ".document" files.
But shouldn't vendored things be ignored totally?

Make sure the following tasks are checked

• Describe the problem / feature
• Write tests for features and bug fixes
• Write code to solve the problem
• Make sure you follow the current code style and write meaningful commit messages without tags

[deivid-rodriguez]

Makes sense to me!

You need to update the Manifest.txt file though by running bin/rake update_manifest, and also, we should make sure our vendor script no longer generates this file, i.e., remove this line.

[deivid-rodriguez]

Thank you @nobu. This idea made sense to me, so I updated it with my small suggestions and will merge it.