docs: remove second mention of btree max length reduction

bmomjian · bmomjian · commit 4217d15d9112 · 2019-05-11T18:24:31.000-04:00
I already added that to the incompatibility section as a separate item.

Reported-by: Peter Geoghegan
diff --git a/doc/src/sgml/release-12.sgml b/doc/src/sgml/release-12.sgml
@@ -641,7 +641,7 @@ Have new btree indexes sort duplicate index entries in heap-storage order (Peter
 </para>
 
 <para>
-This slightly reduces the maximum-allowed length of indexed values.  Indexes <application>pg_upgraded</application> from previous releases will not have this ordering.
+Indexes <application>pg_upgraded</application> from previous releases will not have this ordering.
 </para>
 </listitem>
 
