Update lcharacteristics of G-4387 (maintainability instead of readability)

Author: PhilippSalvisberg

docs/4-language-usage/4-control-structures/3-flow-control/g-4387.md

@@ -1,7 +1,7 @@
 # G-4387: Never use a FOR LOOP for a query that should return not more than one row.
 
 !!! bug "Blocker"
-    Reliability, Efficiency, Readability
+    Reliability, Efficiency, Maintainability
 
 !!! missing "Unsupported in db\* CODECOP Validators"
     Without access to the Oracle Data Dictionary, we cannot determine the number of rows to be processed.