Fix typo in atlases documentation

[GregVernon]

Typo can be seen on https://juliamanifolds.github.io/Manifolds.jl/stable/features/atlases.html

Looks like a missing \ so I added it, though I haven't previewed if that does, in fact, fix it.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.69%. Comparing base (315601e) to head (12dffbf).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #751   +/-   ##
=======================================
  Coverage   99.69%   99.69%           
=======================================
  Files         123      123           
  Lines       11418    11418           
=======================================
  Hits        11383    11383           
  Misses         35       35           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[kellertuer]

Thanks for spotting that, indeed there is a \ missing. I am confident this does not need a preview. It will be visible in the dev-version after merge and be part of the next release then.

Thanks for the PR.