doc: replace @return by Return:

Sphinx expects Return: and not @return to indicate a return value.

find . -name '*.c' -exec \
sed -i 's/^\(\s\)\*\(\s*\)@return\(\s\)/\1*\2Return:\3/' {} \;

find . -name '*.h' -exec \
sed -i 's/^\(\s\)\*\(\s*\)@return\(\s\)/\1*\2Return:\3/' {} \;

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/common/hash.c b/common/hash.c
index 79202e1..9e53545 100644
--- a/common/hash.c
+++ b/common/hash.c
@@ -500,7 +500,7 @@
  * @allow_env_vars:	non-zero to permit storing the result to an environment
  *			variable. If 0 then verify_str is assumed to be an
  *			address, and the * prefix is not expected.
- * @return 0 if ok, non-zero on error
+ * Return: 0 if ok, non-zero on error
  */
 static int parse_verify_sum(struct hash_algo *algo, char *verify_str,
 			    uint8_t *vsum, int allow_env_vars)