message: Fix incorrect backtick usage in inline code
diff: @@ -63,7 +63,7 @@ We need to find out the parent commit in which the PR opened last Monday merged.
  Go to that PR, and find the "bors merged commit $SHA into rust-lang:master at the bottom.
  -Locally, run `export BRANCH_POINT=`git rev-parse $SHA^` in the rust-lang/rust
  +Locally, run `` export BRANCH_POINT=`git rev-parse $SHA^` `` in the rust-lang/rust
  checkout. This should be bors-authored merge into master of the PR before the
  version bump merged.
  