Adding configuration-specific CSR doc

[jquevremont]

First attempt to add configuration-specific CSR lists and descriptions in the user manual.
First attempt to point to a file in another subdirectory (common between user manual and design document). I think we need to PR to test if it creates the expected result in ReadTheDocs.

[github-actions]

✔️ successful run, report available here.

[JeanRochCoulon]

To test the readthedoc generation, you can execute "make singlehtlm" after cloning repo in linux env.

[jquevremont]

To test the readthedoc generation, you can execute "make singlehtml" after cloning repo in linux env.

Thanks for the hint. I tested the include from another directory it looks operational.

@JeanRochCoulon, I need your help to proceed further:

• There is no csr_list.rst in csr-from-ip-xact/cv32a60ax
• Could you change the titles to be more specific in the .rst files as they directly appear in the generated doc? E.g. "CV32A60X CSR descriptions" instead of "REGISTERS CSR CV32A6" in csr-from-ip-xact/cv32a60x/csr.rst

As these are generated files, I do not edit them.

[github-actions]

✔️ successful run, report available here.

[jquevremont]

There is no csr_list.rst in csr-from-ip-xact/cv32a60ax

Also sphinx returns WARNING: toctree contains reference to document 'CSR_CV32A60AX' that doesn't have a title: non link will be generated, so I have added a placeholder instead of this file, while this is fixed.

Could you change the titles to be more specific in the .rst files as they directly appear in the generated doc? E.g. "CV32A60X CSR descriptions" instead of "REGISTERS CSR CV32A6" in csr-from-ip-xact/cv32a60x/csr.rst

I could find a workaround in index.rst with toctree syntax.

FYI @JeanRochCoulon, sphinx returns many such non-blocking warnings, that you might consider fixing in the CSR document generator:

REGISTERS CSR CV32A6
===================
../csr-from-ip-xact/cv32a60x/csr.rst:11: WARNING: Title underline too short.

Unimplemented CSR accessing generates an illegal instruction exception.
--------------------------
../csr-from-ip-xact/cv32a60x/csr.rst:13: WARNING: Title underline too short.

and

MSTATUS:Machine Status Register
--------------------------
../csr-from-ip-xact/cv32a60x/csr.rst:38: WARNING: Inline literal start-string without end-string.
../csr-from-ip-xact/cv32a60x/csr.rst:50: WARNING: Inline literal start-string without end-string.
../csr-from-ip-xact/cv32a60x/csr.rst:56: WARNING: Inline literal start-string without end-string.

[github-actions]

✔️ successful run, report available here.

[jquevremont]

@JeanRochCoulon, can you merge?

[github-actions]

✔️ successful run, report available here.

[JeanRochCoulon]

Sorry for the delay ! I merge