Consistent use of none in docs

[obycode]

Fixed places in the docs that used None or (none).

[codecov]

Codecov Report

Merging #3605 (cc2966b) into develop (dff6c54) will decrease coverage by 0.88%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #3605      +/-   ##
===========================================
- Coverage    31.17%   30.30%   -0.88%     
===========================================
  Files          298      297       -1     
  Lines       276069   275498     -571     
===========================================
- Hits         86070    83481    -2589     
- Misses      189999   192017    +2018     

Impacted Files	Coverage Δ
clarity/src/vm/docs/mod.rs	0.00% <ø> (ø)
testnet/stacks-node/src/tests/bitcoin_regtest.rs	15.92% <0.00%> (-77.03%)	⬇️
testnet/stacks-node/src/tests/epoch_205.rs	30.27% <0.00%> (-67.88%)	⬇️
src/net/atlas/download.rs	7.56% <0.00%> (-66.33%)	⬇️
clarity/src/vm/events.rs	45.27% <0.00%> (-16.92%)	⬇️
src/burnchains/burnchain.rs	59.11% <0.00%> (-14.68%)	⬇️
testnet/stacks-node/src/tests/mod.rs	46.43% <0.00%> (-8.91%)	⬇️
src/net/atlas/db.rs	61.47% <0.00%> (-7.79%)	⬇️
testnet/stacks-node/src/run_loop/mod.rs	91.74% <0.00%> (-7.34%)	⬇️
clarity/src/vm/functions/sequences.rs	46.48% <0.00%> (-4.69%)	⬇️
... and 54 more

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