godot-cpp CMake documentation guideline conformance updates (#11376)

* cmake-updates

Documentation Guideline Conformance
- added sphinx reference name, matching the scons name
- fix admonition formatting
- use proper headings rather than topic::
- reflow due to change of indent.
- add code block language to fix highlighting
- fix bad formatting for bullet points
-  a couple of full stops, colons, and capitilsation
- added a link to the android documentation in the admonition

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Co-authored-by: A Thousand Ships <[email protected]>

Author: enetheru