Use inline code for regression labels

Co-authored-by: Joshua Nelson <[email protected]>

Author: camelid

posts/inside-rust/2020-10-08-regression-labels.md

@@ -20,9 +20,9 @@ We also have labels that help us keep track of regressions so that we can
 prioritize them and fix them quickly if they are severe. We have three
 regression labels, each representing when the regression occurred:
 
-* regression-from-stable-to-nightly
-* regression-from-stable-to-beta
-* regression-from-stable-to-stable
+* `regression-from-stable-to-nightly`
+* `regression-from-stable-to-beta`
+* `regression-from-stable-to-stable`
 
 We recently had a case where a [regression was not caught][internals-thread]
 before a release because the issue was not marked with a regression label.