Fix typos.

Reported-by: Justin Pryzby
Author: Justin Pryzby
Discussion: https://postgr.es/m/20200206021432.GA24549@telsasoft.com

doc/src/sgml/sources.sgml

@@ -511,7 +511,7 @@ Hint:       the addendum
 
    <para>
     There are functions in the backend that will double-quote their own output
-    at need (for example, <function>format_type_be()</function>).  Do not put
+    as needed (for example, <function>format_type_be()</function>).  Do not put
     additional quotes around the output of such functions.
    </para>
 
@@ -880,7 +880,7 @@ BETTER: unrecognized node type: 42
      practices.
     </para>
     <para>
-     Features from later revision of the C standard or compiler specific
+     Features from later revisions of the C standard or compiler specific
      features can be used, if a fallback is provided.
     </para>
     <para>

src/backend/access/transam/README.parallel

@@ -169,7 +169,7 @@ differently because of them.  Right now, we don't even allow that.
 At the end of a parallel operation, which can happen either because it
 completed successfully or because it was interrupted by an error, parallel
 workers associated with that operation exit.  In the error case, transaction
-abort processing in the parallel leader kills of any remaining workers, and
+abort processing in the parallel leader kills off any remaining workers, and
 the parallel leader then waits for them to die.  In the case of a successful
 parallel operation, the parallel leader does not send any signals, but must
 wait for workers to complete and exit of their own volition.  In either

src/backend/storage/buffer/bufmgr.c

@@ -4291,7 +4291,7 @@ ts_ckpt_progress_comparator(Datum a, Datum b, void *arg)
  *
  * *max_pending is a pointer instead of an immediate value, so the coalesce
  * limits can easily changed by the GUC mechanism, and so calling code does
- * not have to check the current configuration. A value is 0 means that no
+ * not have to check the current configuration. A value of 0 means that no
  * writeback control will be performed.
  */
 void

src/backend/storage/sync/sync.c

@@ -216,7 +216,7 @@ SyncPostCheckpoint(void)
 
 		/*
 		 * As in ProcessSyncRequests, we don't want to stop absorbing fsync
-		 * requests for along time when there are many deletions to be done.
+		 * requests for a long time when there are many deletions to be done.
 		 * We can safely call AbsorbSyncRequests() at this point in the loop
 		 * (note it might try to delete list entries).
 		 */

src/include/access/tableam.h

@@ -1199,7 +1199,7 @@ table_tuple_complete_speculative(Relation rel, TupleTableSlot *slot,
  * operation. That's often faster than calling table_insert() in a loop,
  * because e.g. the AM can reduce WAL logging and page locking overhead.
  *
- * Except for taking `nslots` tuples as input, as an array of TupleTableSlots
+ * Except for taking `nslots` tuples as input, and an array of TupleTableSlots
  * in `slots`, the parameters for table_multi_insert() are the same as for
  * table_tuple_insert().
  *