fix typo of docs rule

[oameye]

No description provided.

[github-actions]

Benchmark Results

	master	d2a1958...	master/d2a19580ebaee9...
overhead/acrule/a+2	0.734 ± 0.017 μs	0.766 ± 0.019 μs	0.958
overhead/acrule/a+2+b	0.711 ± 0.016 μs	0.744 ± 0.017 μs	0.955
overhead/acrule/a+b	0.255 ± 0.01 μs	0.268 ± 0.0089 μs	0.95
overhead/acrule/noop:Int	26.2 ± 0.91 ns	26.2 ± 0.92 ns	1
overhead/acrule/noop:Sym	0.0365 ± 0.0048 μs	0.0369 ± 0.0061 μs	0.989
overhead/rule/noop:Int	0.0448 ± 0.00051 μs	0.0452 ± 0.00054 μs	0.992
overhead/rule/noop:Sym	0.0536 ± 0.0027 μs	0.0556 ± 0.0032 μs	0.964
overhead/rule/noop:Term	0.0545 ± 0.0032 μs	0.0558 ± 0.003 μs	0.976
overhead/ruleset/noop:Int	0.131 ± 0.0041 μs	0.129 ± 0.0033 μs	1.01
overhead/ruleset/noop:Sym	0.15 ± 0.0054 μs	0.154 ± 0.0049 μs	0.976
overhead/ruleset/noop:Term	3.5 ± 0.13 μs	3.16 ± 0.13 μs	1.11
overhead/simplify/noop:Int	0.14 ± 0.0024 μs	0.139 ± 0.0019 μs	1.01
overhead/simplify/noop:Sym	0.159 ± 0.0051 μs	0.153 ± 0.0058 μs	1.04
overhead/simplify/noop:Term	0.0376 ± 0.0018 ms	0.0354 ± 0.0017 ms	1.06
overhead/simplify/randterm (+, *):serial	0.0894 ± 0.0011 s	0.0874 ± 0.0011 s	1.02
overhead/simplify/randterm (+, *):thread	0.0507 ± 0.029 s	0.0506 ± 0.033 s	1
overhead/simplify/randterm (/, *):serial	0.213 ± 0.0069 ms	0.211 ± 0.0065 ms	1.01
overhead/simplify/randterm (/, *):thread	0.242 ± 0.0081 ms	0.242 ± 0.0072 ms	1
overhead/substitute/a	0.0641 ± 0.0018 ms	0.0609 ± 0.0015 ms	1.05
overhead/substitute/a,b	0.0561 ± 0.0017 ms	0.0538 ± 0.0015 ms	1.04
overhead/substitute/a,b,c	16.9 ± 0.67 μs	17.4 ± 0.63 μs	0.969
polyform/easy_iszero	31.4 ± 2 μs	28.8 ± 2 μs	1.09
polyform/isone	2.79 ± 0.01 ns	2.79 ± 0.01 ns	1
polyform/iszero	1.21 ± 0.03 ms	1.12 ± 0.037 ms	1.07
polyform/simplify_fractions	1.74 ± 0.044 ms	1.6 ± 0.039 ms	1.09
time_to_load	4.56 ± 0.11 s	4.54 ± 0.016 s	1.01

Benchmark Plots

A plot of the benchmark results have been uploaded as an artifact to the workflow run for this PR.
Go to "Actions"->"Benchmark a pull request"->[the most recent run]->"Artifacts" (at the bottom).

[bowenszhu]

Thanks for catching and fixing this typo!