chore: update Rslib description in README.md #18549

Job	Run time
Check license of dependencies	8s
Spell check	5s
Check Source Changed	5s
Pnpm Lockfile Check	23s
Get Runner Labels / Get Runner Labels	1s
Test Release Linux	0s
Test Release Windows	0s
Test Release Mac	0s
Lint and format code	0s
Rust Changes	0s
Lint and format website	0s
Test Mac	0s
Test Linux / Build	3s
Test Windows / Build	3s
Rust test miri	0s
Rust test	0s
Rust check	0s
Check Rust Unused Dependencies	0s
Test Linux / E2E Testing	0s
Test Linux / Bench	0s
Test Linux / Test Node 18	1s
Test Windows / E2E Testing	0s
Test Windows / Bench	0s
Test Windows / Test Node 18	1s
Failure Notification	0s
	50s

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