tools/check-commits.sh: allow AUTHORS as a prefix in commit message summaries

Currently, the commit message summary line regex in check-commits.sh
allows CONTRIBUTORS but not AUTHORS. Add AUTHORS.

Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>

Author: ajdlinux

tools/check-commits.sh

@@ -23,7 +23,7 @@ for HASH in ${HASHES}; do
 	((COMMITS+=1))
 	SUBJECT=$(git show --format="%s" --no-patch ${HASH})
 	BODY=$(git show --format="%B" --no-patch ${HASH})
-	PATTERN="^(Revert \"|(([a-z0-9/_.-]+|Makefile|CONTRIBUTORS|README.md)(, )?)+:\ [^A-Z].+[^.]$)"
+	PATTERN="^(Revert \"|(([a-z0-9/_.-]+|Makefile|AUTHORS|CONTRIBUTORS|README.md)(, )?)+:\ [^A-Z].+[^.]$)"
 	if ! [[ ${SUBJECT} =~ $PATTERN ]]; then
 		echo "##[error]Wrong commit subject format: '${SUBJECT}'.\
  Please use 'main/affected/package: short change description'.\