Add note about disk out of space errors

Change-Id: I3d03a707254bc62e67909d154eaa857fdcfbed8e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2295823Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#787846}

docs/clang_sheriffing.md

@@ -26,6 +26,11 @@ but that is sadly not always the case.
 
 [TOC]
 
+## Disk out of space
+
+If there are any issues with disk running out of space, file a go/bug-a-trooper
+bug, for example https://crbug.com/1105134.
+
 ## Is it the compiler?
 
 Chromium does not always build and pass tests in all configurations that