Fix Typo

Author: GithubAnon0000

src/faqs/fsrs.md

@@ -4,5 +4,5 @@
 You might have optimized your FSRS parameters. If you optimize your parameters,
 FSRS might determine that the intervals should be shorter than it previously
 predicted. The reason is that the
-[Difficulty, Stability, Reterievability](https://github.com/open-spaced-repetition/fsrs4anki/wiki/abc-of-fsrs)
+[Difficulty, Stability, Retrievability](https://github.com/open-spaced-repetition/fsrs4anki/wiki/abc-of-fsrs)
 values are recalculated, once you optimize your FSRS parameters.