Fix details missed by dynamic shared memory patch.

Additional documentation update, and a comment fix.

Both issues reported by Amit Kapila.

doc/src/sgml/storage.sgml

@@ -72,6 +72,12 @@ Item
  <entry>Subdirectory containing transaction commit status data</entry>
 </row>
 
+<row>
+ <entry><filename>pg_dynshmem</></entry>
+ <entry>Subdirectory containing files used by the dynamic shared memory
+  subsystem</entry>
+</row>
+
 <row>
  <entry><filename>pg_multixact</></entry>
  <entry>Subdirectory containing multitransaction status data

src/backend/utils/resowner/resowner.c

@@ -1301,7 +1301,7 @@ ResourceOwnerRememberDSM(ResourceOwner owner, dsm_segment *seg)
 }
 
 /*
- * Forget that a temporary file is owned by a ResourceOwner
+ * Forget that a dynamic shmem segment is owned by a ResourceOwner
  */
 void
 ResourceOwnerForgetDSM(ResourceOwner owner, dsm_segment *seg)