Correct a few typos in comments

[JJCUBER]

PR Prelude

Thank you for working on YCM! :)

Please complete these steps and check these boxes (by putting an x inside
the brackets) before filing your PR:

• I have read and understood YCM's CONTRIBUTING document.
• I have read and understood YCM's CODE_OF_CONDUCT document.
• I have included tests for the changes in my PR. If not, I have included a
  rationale for why I haven't.
• I understand my PR may be closed if it becomes obvious I didn't
  actually perform all of these steps.

Why this change is necessary and useful

While this is quite a minor change, I feel that it helps with the readability and flow of the source code for people first familiarizing themselves with it (and/or people coming back to it after a while).

I did not include tests since only comments were modified.

---

This change is 

[puremourning]

Cheers.

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: 1 of 2 LGTMs obtained (waiting on @JJCUBER)

[bstaletic]

Thanks!

[codecov]

Codecov Report

Merging #4220 (a73fbdf) into master (0497bb0) will decrease coverage by 0.30%.
The diff coverage is 0.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4220      +/-   ##
==========================================
- Coverage   89.74%   89.44%   -0.30%     
==========================================
  Files          34       34              
  Lines        4425     4425              
==========================================
- Hits         3971     3958      -13     
- Misses        454      467      +13     

[bstaletic]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: complete! 2 of 2 LGTMs obtained (waiting on @JJCUBER)

[mergify]

Thanks for sending a PR!