[INFRA] Drop numeric XX- from markdown file names

[effigies]

Closes #1323.

[codecov]

Codecov Report

Base: 88.50% // Head: 88.39% // Decreases project coverage by -0.10% ⚠️

Coverage data is based on head (b5abfb7) compared to base (6d71b6a).
Patch has no changes to coverable lines.

❗ Current head b5abfb7 differs from pull request most recent head 8f1728e. Consider uploading reports for the commit 8f1728e to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1345      +/-   ##
==========================================
- Coverage   88.50%   88.39%   -0.11%     
==========================================
  Files          11       11              
  Lines        1087     1086       -1     
==========================================
- Hits          962      960       -2     
- Misses        125      126       +1     

Impacted Files	Coverage Δ
tools/schemacode/bidsschematools/render/tables.py	86.29% <ø> (ø)
tools/schemacode/bidsschematools/validator.py	95.89% <0.00%> (-0.36%)	⬇️

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