docs: clarify user_id vs uid for fuse

[ghost]

Fixes: #5723

[codecov-commenter]

Codecov Report

Merging #5958 (5d6e9c8) into master (c6559f0) will decrease coverage by 0.22%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #5958      +/-   ##
==========================================
- Coverage   83.32%   83.10%   -0.23%     
==========================================
  Files          38       38              
  Lines       10359    10359              
  Branches     1710     1710              
==========================================
- Hits         8632     8609      -23     
- Misses       1221     1238      +17     
- Partials      506      512       +6     

Impacted Files	Coverage Δ
src/borg/archiver.py	80.26% <ø> (ø)
src/borg/platform/__init__.py	72.00% <0.00%> (-12.00%)	⬇️
src/borg/platform/base.py	77.77% <0.00%> (-3.42%)	⬇️
src/borg/helpers/misc.py	77.34% <0.00%> (-1.66%)	⬇️
src/borg/helpers/fs.py	85.52% <0.00%> (-1.32%)	⬇️
src/borg/xattr.py	49.41% <0.00%> (-1.18%)	⬇️
src/borg/archive.py	81.46% <0.00%> (-0.64%)	⬇️

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[ghost]

PTAL.

[ThomasWaldmann]

some grammar nitpicks and one thing that is still unclear.

[ThomasWaldmann]

Thanks!