[MISC] Reorder appendices

[tsalo]

Closes #1204.

Changes proposed:

• Move the glossary to the main part of the specification, under the changelog.
• Reorder appendices.
• Remove numbering from appendix titles and filenames.

[codecov]

Codecov Report

Merging #1256 (c31c3c1) into master (9ad23e8) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1256   +/-   ##
=======================================
  Coverage   88.53%   88.53%           
=======================================
  Files           6        6           
  Lines        1055     1055           
=======================================
  Hits          934      934           
  Misses        121      121           

Impacted Files	Coverage Δ
tools/schemacode/bidsschematools/render.py	92.80% <100.00%> (ø)

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[effigies]

Verifying https://bids-specification--1256.org.readthedocs.build/en/1256/99-appendices/14-glossary.html redirects correctly.

[sappelhoff]

if we merge this we need to push adjustments to the NIRS pr

[Remi-Gau]

Had a quick look and nothing stands out as out of order.

[tsalo]

This now has three approvals. I'm thinking this change is big enough that we should wait the 5 days. What do you all think?

[sappelhoff]

thanks @tsalo