docs: cleanup documentation

Related to https://repo1.dso.mil/platform-one/big-bang/bigbang/-/issues/490

added gatekeeper kinddocs statusreview labels

Some of the docs removed were added by integration @msbrown47 @kenna81. I will like them to provide feedback before the MR is merged.

requested review from @toladipupo

requested review from @msbrown47 and @kenna81

@msbrown47 and @kenna81 I attempted to consolidate the information unless it was obsolete. So, the files I deleted, I tried to move the content into another file (for example overview went into readme)

I went through and the changes looked good to me. Mostly just shifting the information around and cleaning up links and stuff. I'm going to approve.

approved this merge request

approved this merge request

merged

mentioned in commit ca9829ac