Adding .readthedocs.yaml file, Moving SRAM outside digital directory, Fix all warnings, Move I/O and SRAM docs to their repositories

[mohanad0mohamed]

Fixes #26 Fixes #15 Fixes #20 Fixes #11 Fixes #12

• The file .readthedocs.yaml is added.

• The SRAM directory is now in a new directory called IP, Standard Cells are in digital, and I/Os are in IO.

• Fixed all warnings happens when building read-the-docs.

• Moved IO docs from this repository into globalfoundries-pdk-libs-gf180mcu_fd_io.

• Moved SRAM docs from this repository into globalfoundries-pdk-ip-gf180mcu_fd_ip_sram.

• [x] .readthedocs.yaml is added.

• [x] SRAM directory is outside digital directory.

• [x] Building the docs locally passes without any warnings.

• [x] I/O documentation is moved.

• [x] SRAM documentation is moved.

[mohanad0mohamed]

Looks like I have a problem in building the docs from symbolic links. I will check them again.

[mithro]

Please send one pull request per issue fixed.