Clarify vote counting in the code style template

Code style proposals may be upvoted by maintainers but also be other
contributors which is great!

This commit highlights the fact that we only count maintainers' upvotes.

.gitlab/issue_templates/Coding style proposal.md

@@ -5,7 +5,7 @@ Please describe the proposal and add a link to the source (for example, http://w
 -->
 
 - [ ] Mention the proposal in the next backend weekly call and the #backend channel to encourage contribution
-- [ ] Proceed with the proposal once 50% of the maintainers have weighed in, and 80% of the votes are :+1:
+- [ ] Proceed with the proposal once 50% of the maintainers have weighed in, and 80% of their votes are :+1:
 - [ ] Once approved, mention it again in the next backend weekly call and the #backend channel