doc: Fix PQsslAttribute docs for compression

The compression parameter to PQsslAttribute has never returned the
compression method used, it has always returned "on" or "off since
it was added in commit 91fa7b4719ac. Backpatch through v10.

Reviewed-by: Tom Lane 
Discussion: https://postgr.es/m/B9EC60EC-F665-47E8-A221-398C76E382C9@yesql.se
Backpatch-through: v10

diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 8908f775df3155fdc70f857faabcf1ccd898772c..026b0ec46bb2b53bc89045d9e47137cf0adff1ae 100644 (file)
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -2564,9 +2564,7 @@ const char *PQsslAttribute(const PGconn *conn, const char *attribute_name);
          compression
           
            
-            If SSL compression is in use, returns the name of the compression
-            algorithm, or "on" if compression is used but the algorithm is
-            not known. If compression is not in use, returns "off".
+            Returns "on" if SSL compression is in use, else it returns "off".