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[bot]]

• :white_check_mark:login: crsantos / (bdd8939fc44d64132b76e3f90c578ce33d36ac84)

The committers listed above are authorized under a signed CLA.

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

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

```diff @@ 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.