Add Commonmarker to related projects

[gjtorikian]

As the title says! I also:

• Alphabetized the languages (OCD)
• Moved the note about GFM implementation higher up

[github-actions]

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
./bench.sh ./comrak-f003382	317.9 ± 1.3	316.0	321.7	2.94 ± 0.02
./bench.sh ./comrak-main	318.9 ± 2.8	316.1	329.8	2.95 ± 0.03
./bench.sh ./pulldown-cmark	108.2 ± 0.4	107.3	108.9	1.00
./bench.sh ./cmark-gfm	114.0 ± 1.0	112.4	116.5	1.05 ± 0.01
./bench.sh ./markdown-it	473.9 ± 1.2	470.8	475.9	4.38 ± 0.02

Run on Tue Mar 11 16:30:34 UTC 2025

[kivikakk]

Yippee! Thank you!