Moving IO docs from gf180mcu-pdk

[mohanad0mohamed]

Fixes https://github.com/google/gf180mcu-pdk/issues/12

• Moved all documentations in docs directory.

• Made symbolic link for it in gf180mcu-pdk

• [x] Built locally with no errors

[mithro]

This pull request should include a link to the pull request at https://github.com/google/gf180mcu-pdk/pull/34 in the description.

[mohanad0mohamed]

Made the requested changes

[mohanad0mohamed]

I have retrieved contributing.rst and code_of_conduct.rst but not inside docs, instead I put them outside not to produce warnings.