Correct typos in documentation

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (456eeef) 95.92% compared to head (960931c) 95.92%. Report is 3 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #133 +/- ## ======================================= Coverage 95.92% 95.92% ======================================= Files 16 16 Lines 1793 1793 ======================================= Hits 1720 1720 Misses 73 73 ``` | [Flag](https://app.codecov.io/gh/BioJulia/Automa.jl/pull/133/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BioJulia) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/BioJulia/Automa.jl/pull/133/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BioJulia) | `95.92% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BioJulia#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.