Fix some warning blocks that contain Markdown

Content inside of an HTML element only gets interpreted as Markdown
(as opposed to HTML) if its separated by line breaks from the HTML tags.

Author: fmease

src/infra/docs/bors/queue-resync.md

@@ -3,6 +3,7 @@
 bors queue page: <https://bors.rust-lang.org/queue/rust>.
 
 <div class="warning">
+
 **WARNING**: You should only do this if you have bors `r+` permissions on the
 rust-lang/rust repo. Please do not synchronize if you do not have `r+` permissions
 even if you have write access to the repo, as you will be unable to perform the
@@ -14,6 +15,7 @@ be recollected, and 15 minutes after that to kick out PRs that should not be in
 the tree.
 
 **DO NOT CLICK THIS BUTTON IF YOU ARE NOT ABLE TO HANDLE THE CLEANUP.**
+
 </div>
 
 Sometimes you have to do a bors queue sync for various reasons. This is not

src/release/issue-triaging.md

@@ -182,7 +182,9 @@ Anything related to the compiler implementation, such as diagnostics and ICEs.
 ### Creating labels
 
 <div class="warning">
+
 Triagebot needs to support `@rustbot label: xxx` usages terminated with a period or whitespace (as inline invocation), so the label name must consist of only alphanumeric or hyphen (`-`) or underscore (`_`) characters.
+
 </div>
 
 - Check existing labels to make sure you're not duplicating them.