Consistently mention 'SELECT pg_reload_conf()' in config files

Previously we only mentioned SIGHUP and 'pg_ctl reload' in
postgresql.conf and pg_hba.conf.

src/backend/libpq/pg_hba.conf.sample

@@ -59,11 +59,11 @@
 # its special character, and just match a database or username with
 # that name.
 #
-# This file is read on server startup and when the postmaster receives
-# a SIGHUP signal.  If you edit the file on a running system, you have
-# to SIGHUP the postmaster for the changes to take effect.  You can
-# use "pg_ctl reload" to do that.
-
+# This file is read on server startup and when the server receives a
+# SIGHUP signal.  If you edit the file on a running system, you have to
+# SIGHUP the server for the changes to take effect, run "pg_ctl reload",
+# or execute "SELECT pg_reload_conf()".
+#
 # Put your actual configuration here
 # ----------------------------------
 #

src/backend/utils/misc/postgresql.conf.sample

@@ -16,9 +16,9 @@
 #
 # This file is read on server startup and when the server receives a SIGHUP
 # signal.  If you edit the file on a running system, you have to SIGHUP the
-# server for the changes to take effect, or use "pg_ctl reload".  Some
-# parameters, which are marked below, require a server shutdown and restart to
-# take effect.
+# server for the changes to take effect, run "pg_ctl reload", or execute
+# "SELECT pg_reload_conf()".  Some parameters, which are marked below,
+# require a server shutdown and restart to take effect.
 #
 # Any parameter can also be given as a command-line option to the server, e.g.,
 # "postgres -c log_connections=on".  Some parameters can be changed at run time