Fix typo

[MiguelGarcaoSilva]

Fixed typo in mmotifs docs

Pull Request Checklist

Below is a simple checklist but please do not hesitate to ask for assistance!

• [x] Fork, clone, and checkout the newest version of the code
• [x] Create a new branch
• [x] Make necessary code changes
• [ ] Install black (i.e., python -m pip install black or conda install -c conda-forge black)
• [ ] Install flake8 (i.e., python -m pip install flake8 or conda install -c conda-forge flake8)
• [ ] Install pytest-cov (i.e., python -m pip install pytest-cov or conda install -c conda-forge pytest-cov)
• [ ] Run black . in the root stumpy directory
• [ ] Run flake8 . in the root stumpy directory
• [ ] Run ./setup.sh && ./test.sh in the root stumpy directory
• [ ] Reference a Github issue (and create one if one doesn't already exist)

[codecov[bot]]

Codecov Report

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

Project coverage is 97.42%. Comparing base (2770a88) to head (f054744).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1017 +/- ## ======================================= Coverage 97.42% 97.42% ======================================= Files 89 89 Lines 14934 14934 ======================================= Hits 14549 14549 Misses 385 385 ```

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

[seanlaw]

@MiguelGarcaoSilva Thank you for fixing this typo!