MDEV-37908: Replace perror link with GitBook

Replace the KB link in `extra/perror` (from
MDEV-34168) with a computed GitBook docs link

Reviewed-by: Daniel Black <[email protected]>

Author: ParadoxV5

extra/perror.c

@@ -360,8 +360,13 @@ int main(int argc,char *argv[])
       {
         found= 1;
         if (verbose)
+        {
+          int hundred= code / 100;
           printf("MariaDB error code %3d (%s): %s\n"
-                 "Learn more: https://mariadb.com/kb/en/e%3d/\n", code, name, msg, code);
+                 "Learn more: https://mariadb.com/docs/server/reference/"
+                 "error-codes/mariadb-error-codes-%d00-to-%d99/e%3d\n",
+                 code, name, msg, hundred, hundred, code);
+        }
         else
           puts(msg);
       }

mysql-test/main/perror-win.result

@@ -3,6 +3,6 @@ Win32 error code 150: System trace information was not specified in your CONFIG.
 OS error code  23:  Too many open files in system
 Win32 error code 23: Data error (cyclic redundancy check).
 MariaDB error code 1062 (ER_DUP_ENTRY): Duplicate entry '%-.192T' for key %d
-Learn more: https://mariadb.com/kb/en/e1062/
+Learn more: https://mariadb.com/docs/server/reference/error-codes/mariadb-error-codes-1000-to-1099/e1062
 Win32 error code 1062: The service has not been started.
 Illegal error code: 30000

mysql-test/main/perror.result

@@ -1,10 +1,10 @@
 Illegal error code: 10000
 MariaDB error code 1062 (ER_DUP_ENTRY): Duplicate entry '%-.192T' for key %d
-Learn more: https://mariadb.com/kb/en/e1062/
+Learn more: https://mariadb.com/docs/server/reference/error-codes/mariadb-error-codes-1000-to-1099/e1062
 MariaDB error code 1408 (ER_STARTUP): %s: ready for connections.
 Version: '%s'  socket: '%s'  port: %d  %s
-Learn more: https://mariadb.com/kb/en/e1408/
+Learn more: https://mariadb.com/docs/server/reference/error-codes/mariadb-error-codes-1400-to-1499/e1408
 MariaDB error code 1459 (ER_TABLE_NEEDS_UPGRADE): Upgrade required. Please do "REPAIR %s %`s" or dump/reload to fix it!
-Learn more: https://mariadb.com/kb/en/e1459/
+Learn more: https://mariadb.com/docs/server/reference/error-codes/mariadb-error-codes-1400-to-1499/e1459
 MariaDB error code 1461 (ER_MAX_PREPARED_STMT_COUNT_REACHED): Can't create more than max_prepared_stmt_count statements (current value: %u)
-Learn more: https://mariadb.com/kb/en/e1461/
+Learn more: https://mariadb.com/docs/server/reference/error-codes/mariadb-error-codes-1400-to-1499/e1461