[DOC] Fix typos in protobuf comments

[Calileus]

Reference to a related issue in the repository

• Minor documentation typos in .proto files #915

Add a description

Few comments in the .proto files contain minor grammatical typos that could be corrected to improve documentation readability and consistency.

Some questions to ask:
What is this change?

• A minor documentation improvement.
  What does it fix?
• Some documentation typos.
  Is this a bug fix or a feature? Does it break any existing functionality or force me to update to a new version?
  How has it been tested?
• No functional changes, minor comments update only.

Take this checklist as orientation for yourself, if this PR is ready for the Change Control Board:

• My suggestion follows the style and contributors guidelines.
• I have taken care about the message documentation and the fields and enums documentation.
• I have done the DCO signoff.
• My changes generate no errors when passing CI tests.
• I have successfully implemented and tested my fix/feature locally.
• Appropriate reviewer(s) are assigned.

If you can’t check all of them, please explain why.
If all boxes are checked or commented and you have achieved at least one positive review, you can assign the label ReadyForCCBReview!

[pmai]

Looks good to me, to be approved by the CCB.