chore: docs cleanup

[rymnc]

Fixes the docs in rln/src/hashers.rs

[github-actions]

Benchmark for f4d262d

Click to view benchmark

Test	Base	PR	%
FullMerkleTree::delete	1319.8±65.60ns	1321.4±63.22ns	+0.12%
FullMerkleTree::get	0.0±0.00ns	0.0±0.00ns	NaN%
FullMerkleTree::override_range	3.3±0.18µs	3.4±0.18µs	+3.03%
FullMerkleTree::set	1332.1±58.61ns	1314.0±55.81ns	-1.36%
OptimalMerkleTree::compute_root	1540.8±64.67ns	1509.2±76.10ns	-2.05%
OptimalMerkleTree::delete	1491.3±73.98ns	1502.1±70.89ns	+0.72%
OptimalMerkleTree::get	31.2±1.77ns	31.6±1.38ns	+1.28%
OptimalMerkleTree::override_range	7.7±0.41µs	7.6±0.34µs	-1.30%
OptimalMerkleTree::set	1472.3±82.67ns	1522.1±78.60ns	+3.38%

[github-actions]

Benchmark for f4d262d

Click to view benchmark

Test	Base	PR	%
Pmtree::compute_root	2.3±0.05ns	2.3±0.05ns	0.00%
Pmtree::get	540.9±12.48ns	542.0±11.14ns	+0.20%
Pmtree::override_range	204.9±10.93µs	207.0±15.95µs	+1.02%
Pmtree::set	81.8±1.17µs	81.0±1.21µs	-0.98%
Pmtree:delete	80.7±1.49µs	81.9±0.92µs	+1.49%