doc fix

[saroh]

mainly updates schema fast field doc
various lint elsewhere
closes #1232

[codecov-commenter]

Codecov Report

Merging #1391 (5c8cf6b) into main (83d0c13) will decrease coverage by 0.00%.
The diff coverage is 76.00%.

@@            Coverage Diff             @@
##             main    #1391      +/-   ##
==========================================
- Coverage   94.29%   94.29%   -0.01%     
==========================================
  Files         236      236              
  Lines       43418    43433      +15     
==========================================
+ Hits        40942    40953      +11     
- Misses       2476     2480       +4     

Impacted Files	Coverage Δ
query-grammar/src/occur.rs	100.00% <ø> (ø)
src/core/index.rs	92.60% <ø> (ø)
src/core/index_meta.rs	94.36% <ø> (ø)
src/core/segment_reader.rs	91.16% <ø> (ø)
src/docset.rs	67.50% <ø> (ø)
src/fieldnorm/mod.rs	100.00% <ø> (ø)
src/fieldnorm/reader.rs	100.00% <ø> (ø)
src/indexer/merge_policy.rs	88.88% <ø> (ø)
src/positions/mod.rs	100.00% <ø> (ø)
src/positions/reader.rs	100.00% <ø> (ø)
... and 22 more

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[fulmicoton]

Can you run make fmt? The CI is catching some formatting errors.