Update CONTRIBUTING to release workflow in CI

[mzabaluev]

As there is now the release workflow triggered on release tags,
update the release process instructions to take account of it.

[codecov-commenter]

Codecov Report

Merging #1283 (d83722e) into main (0f6ce75) will increase coverage by 0.0%.
The diff coverage is n/a.

❗ Current head d83722e differs from pull request most recent head 0390923. Consider uploading reports for the commit 0390923 to get more accurate results

@@          Coverage Diff          @@
##            main   #1283   +/-   ##
=====================================
  Coverage   64.1%   64.1%           
=====================================
  Files        271     271           
  Lines      24308   24308           
=====================================
+ Hits       15584   15592    +8     
+ Misses      8724    8716    -8     

Impacted Files	Coverage Δ
tendermint/src/timeout.rs	84.2% <0.0%> (-1.8%)	⬇️
light-client-verifier/src/types.rs	38.4% <0.0%> (+0.2%)	⬆️
testgen/src/header.rs	84.0% <0.0%> (+0.5%)	⬆️
testgen/src/commit.rs	91.3% <0.0%> (+0.6%)	⬆️
rpc/src/client/transport/router.rs	82.5% <0.0%> (+0.6%)	⬆️
testgen/src/validator.rs	87.5% <0.0%> (+0.7%)	⬆️
testgen/src/vote.rs	85.8% <0.0%> (+1.6%)	⬆️
tendermint/src/block/commit_sig.rs	80.3% <0.0%> (+1.9%)	⬆️

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