Apply suggestions from code review

Co-Authored-By: Santiago Pastorino <[email protected]>

Author: oli-obk

.github/ISSUE_TEMPLATE/major_change.md

@@ -12,7 +12,7 @@ assignees: ''
 If you'd like to propose a major change to do to rustc, you've come to
 the right place! To do so, please write-up your proposal in this issue.
 
-Describe your major change in a sentence or two under the TLDR section.
+Describe your major change in a sentence or two under the TL;DR section.
 
 If available, add links and more descriptions in the "Links and Details" section.
 Note: it is not expected that you write a fully fleshed out proposal there.
@@ -25,7 +25,7 @@ You can look at [the experts map](https://github.com/rust-lang/compiler-team/blo
 Oh, and please delete this section before you open the issue -- but
 keep the others!
 
-# TLDR
+# TL;DR
 
 # Links and Details