docs: Update link to contributing guide

[DamienIrving]

Just noticed a broken link while reviewing for JOSS.
openjournals/joss-reviews#6060

[nicrie]

Good catch thanks for the fix !

[codecov-commenter]

Codecov Report

Attention: 66 lines in your changes are missing coverage. Please review.

Comparison is base (0f95d04) 94.21% compared to head (11c1208) 94.31%.
Report is 46 commits behind head on main.

Files	Patch %	Lines
xeofs/utils/numba_utils.py	20.96%	49 Missing ⚠️
xeofs/data_container/data_container.py	88.88%	3 Missing ⚠️
xeofs/preprocessing/stacker.py	72.72%	3 Missing ⚠️
xeofs/models/_base_cross_model.py	96.07%	2 Missing ⚠️
xeofs/models/_base_model.py	96.07%	2 Missing ⚠️
xeofs/models/decomposer.py	86.66%	2 Missing ⚠️
xeofs/preprocessing/preprocessor.py	88.88%	2 Missing ⚠️
xeofs/utils/xarray_utils.py	88.88%	2 Missing ⚠️
xeofs/utils/io.py	97.95%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #129      +/-   ##
==========================================
+ Coverage   94.21%   94.31%   +0.09%     
==========================================
  Files          71       73       +2     
  Lines        5823     6083     +260     
==========================================
+ Hits         5486     5737     +251     
- Misses        337      346       +9     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.