chore: Updating root README.md with slack contacts

[crsantos]

What

• Updating root README.md with
  • slack contacts
  • Contributing link
• Removing some markdown warnings

[linux-foundation-easycla]

• ✅login: crsantos / (bdd8939)

The committers listed above are authorized under a signed CLA.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (297d91f) 66.34% compared to head (bdd8939) 66.38%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #520      +/-   ##
==========================================
+ Coverage   66.34%   66.38%   +0.04%     
==========================================
  Files         336      336              
  Lines       14466    14466              
==========================================
+ Hits         9597     9603       +6     
+ Misses       4869     4863       -6     

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[nachoBonafonte]

Thanks for your contribution.