project: fix Multicast link in README

[twittemb]

Description

This PR fixes the broken Multicast link in the README file.

Checklist

• this PR is based on the main branch and is up-to-date, if not please rebase your branch on the top of main
• the commits inside this PR have explicit commit messages
• unit tests cover the new feature or the bug fix
• the feature is documented in the README.md if it makes sense
• the CHANGELOG is up-to-date

[codecov-commenter]

Codecov Report

Merging #10 (3de0007) into main (d80d509) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #10   +/-   ##
=======================================
  Coverage   97.32%   97.32%           
=======================================
  Files          44       44           
  Lines        2243     2243           
=======================================
  Hits         2183     2183           
  Misses         60       60           

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