[MOD-8365] Update datatypes and metric support in README

[meiravgri]

This PR enhances the README with:

• A metrics summary table describing supported distance metrics (L2, IP, Cosine) and their value ranges.
• A short explanation of supported data types and SIMD usage.
• Two detailed tables showing supported SIMD instruction sets for x86 and ARM architectures across all data types.

https://redislabs.atlassian.net/browse/MOD-8365

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.29%. Comparing base (0929890) to head (1598205).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #686   +/-   ##
=======================================
  Coverage   96.29%   96.29%           
=======================================
  Files         111      111           
  Lines        6288     6288           
=======================================
  Hits         6055     6055           
  Misses        233      233           

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[github-actions]

Backport failed for 8.0, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin 8.0
git worktree add -d .worktree/backport-686-to-8.0 origin/8.0
cd .worktree/backport-686-to-8.0
git switch --create backport-686-to-8.0
git cherry-pick -x 5ba2efa9d22a7cc3169d981a104404586d14b9ba