doc: update PG history as over "three decades"

Reported-by: Pierre 
Discussion: https://postgr.es/m/168724660637.399156.7642965215720120947@wrigleys.postgresql.org

Backpatch-through: 11

diff --git a/doc/src/sgml/history.sgml b/doc/src/sgml/history.sgml
index aa171823a8d69e8f025a54b8304198e9b73c7fc3..a2aa19da024181da61d03b7c3ee6c07b1971c5b0 100644 (file)
--- a/doc/src/sgml/history.sgml
+++ b/doc/src/sgml/history.sgml
@@ -12,7 +12,7 @@
   The object-relational database management system now known as
   PostgreSQL is derived from the
   POSTGRES package written at the
-  University of California at Berkeley.  With over two decades of
+  University of California at Berkeley.  With over three decades of
   development behind it, PostgreSQL is now
   the most advanced open-source database available anywhere.