PQ README

[jakemas]

Description of changes:

To better communicate our current support for PQ algorithms in AWS-LC and their integrations, we add the first draft of a PQ README documentation. This documentation is aimed to help users of AWS-LC understand which PQ algorithms are provided, give more details into their security levels, key/signature/ciphertext sizes.

This is a living document that will continue to be updated over time. If there is any feedback/additions/amendments please contribute them directly either as a review suggestion, so there is an explicit change to capture.

Call-outs:

• is crypto/fipsmodule/PQREADME.md the correct location for this documentation? I selected this location to be consistent with similar documentation (https://github.com/aws/aws-lc/blob/main/crypto/fipsmodule/FIPS.md)
• ASCII table appears out of alignment in raw text, but renders correctly as markdown.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.68%. Comparing base (90d2a34) to head (9672b8a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1932      +/-   ##
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+ Coverage   78.66%   78.68%   +0.01%     
==========================================
  Files         585      585              
  Lines      100849   100849              
  Branches    14297    14297              
==========================================
+ Hits        79336    79349      +13     
+ Misses      20876    20865      -11     
+ Partials      637      635       -2     

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