Update Contribution.md

[Fhrozen]

What?

Add instructions to use Github Actions locally.

Why?

To reproduce CI locally.

[codecov]

Codecov Report

Merging #5352 (811a35b) into master (87a7b08) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #5352      +/-   ##
==========================================
- Coverage   76.11%   76.11%   -0.01%     
==========================================
  Files         672      672              
  Lines       59859    59859              
==========================================
- Hits        45563    45561       -2     
- Misses      14296    14298       +2     

Flag	Coverage Δ
test_configuration_espnet2	∅ <ø> (∅)
test_integration_espnet1	65.93% <ø> (ø)
test_integration_espnet2	47.77% <ø> (-0.01%)	⬇️
test_python_espnet1	20.51% <ø> (ø)
test_python_espnet2	51.35% <ø> (ø)
test_utils	23.17% <ø> (ø)

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see 1 file with indirect coverage changes

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[sw005320]

LGTM.
I fixed some typos.