Fix s/intidb/initdb/ typo.

Reported-By: Michael Paquier
Discussion: https://postgr.es/m/CAB7nPqTfaKAYZ4wuUM-W8kc4VnXrxX1=5-a9i==VoUPTMFpsgg@mail.gmail.com

src/include/pg_config_manual.h

@@ -14,7 +14,7 @@
  */
 
 /*
- * This is default value for wal_segment_size to be used at intidb when run
+ * This is default value for wal_segment_size to be used at initdb when run
  * without --walsegsize option. Must be a valid segment size.
  */
 #define DEFAULT_XLOG_SEG_SIZE	(16*1024*1024)