GitLab

Remove markdown extension which isn't supported on github.

PiperOrigin-RevId: 261321329

ee3aa831 added a broken link
which results in 404. The broken part is reference to a
nonexistent file "CheatSheet.md" instead of "cheet_sheet.md".

This line directly contradicts the warning that google mock spits out on unused mock calls:
```
NOTE: You can safely ignore the above warning unless this call should not happen.  Do not suppress it by blindly adding an EXPECT_CALL() if you don't mean to enforce the call.  See https://github.com/google/googletest/blob/master/googlemock/docs/CookBook.md#knowing-when-to-expect for details.
```
One or the other should be changed, and I believe the advice in this file is incorrect.

Removing make and automake. The only supported build systems are Bazel internally and CMake community supported

Rename AdvancedGuide.md to advanced.md and adjust the links. 
Part of documentation rationalization work

move only types docs

The document itself uses lambdas later, all the scaffolding to
work around lack of lambdas should be considered for removal, but
that is much larger an effort than I can commit to.

SeArrayArgument => SetArrayArgument

The old language might mislead someone into thinking that the access level on the base class itself was changed.