Fix typo functoin -> function (#12218)

functoin -> function

src/db.c

@@ -2112,7 +2112,7 @@ void getKeysFreeResult(getKeysResult *result) {
  * 'firstKeyOfs': firstkey index.
  * 'keyStep': the interval of each key, usually this value is 1.
  * 
- * The commands using this functoin have a fully defined keyspec, so returning flags isn't needed. */
+ * The commands using this function have a fully defined keyspec, so returning flags isn't needed. */
 int genericGetKeys(int storeKeyOfs, int keyCountOfs, int firstKeyOfs, int keyStep,
                     robj **argv, int argc, getKeysResult *result) {
     int i, num;