Added policy changes

[jcarlosroldan]

Description

• Listed all policies not supported anymore (layer-normalized)
• Listed all policies not supported for the time being (LSTM)

Motivation and Context

See this comment on issue 106.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)

Checklist:

• I've read the CONTRIBUTION guide (required)
• I have updated the changelog accordingly (required).
• My change requires a change to the documentation.
• I have updated the tests accordingly (required for a bug fix or a new feature).
• I have updated the documentation accordingly.
• I have reformatted the code using make format (required)
• I have checked the codestyle using make check-codestyle and make lint (required)
• I have ensured make pytest and make type both pass. (required)
• I have checked that the documentation builds using make doc (required)

Note: You can run most of the checks using make commit-checks.

Note: we are using a maximum length of 127 characters per line

[araffin]

Hello,
thanks for the PR, please do not forget to update the changelog (c.f. contributing guide and PR checklist).

[araffin]

closing in favor of #450