doc: Improve claim about location of pg_service.conf

The previous wording claimed that the file was always in /etc, but of
course this varies with the installation layout.  Write instead that it
can be found via `pg_config --sysconfdir`.  Even though this is still
somewhat incorrect because it doesn't account of moved installations, it
at least conveys that the location depends on the installation.

diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 4593051a9c39d3f14a9f71c74f018c9f3e0f818c..8a2af4aab4d4daa558d33ae3224dd6f232cfede9 100644 (file)
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -6958,7 +6958,7 @@ myEventProc(PGEventId evtId, void *evtInfo, void *passThrough)
    at ~/.pg_service.conf or the location
    specified by the environment variable PGSERVICEFILE,
    or it can be a system-wide file
-   at /etc/pg_service.conf or in the directory
+   at `pg_config --sysconfdir`/pg_service.conf or in the directory
    specified by the environment variable
    PGSYSCONFDIR.  If service definitions with the same
    name exist in the user and the system file, the user file takes