doc: Fix grammatical error in partitioning docs

Reported-by: Amit Langote
Discussion: https://postgr.es/m/CA+HiwqGZFkKi0TkBGYpr2_5qrRAbHZoP47AP1BRLUOUkfQdy_A@mail.gmail.com
Backpatch-through: 10

doc/src/sgml/ddl.sgml

@@ -4113,9 +4113,9 @@ EXPLAIN SELECT count(*) FROM measurement WHERE logdate >= DATE '2008-01-01';
    <para>
     It is also important to consider the overhead of partitioning during
     query planning and execution.  The query planner is generally able to
-    handle partition hierarchies up a few hundred partitions fairly well,
-    provided that typical queries allow the query planner to prune all but a
-    small number of partitions.  Planning times become longer and memory
+    handle partition hierarchies with up to a few hundred partitions fairly
+    well, provided that typical queries allow the query planner to prune all
+    but a small number of partitions.  Planning times become longer and memory
     consumption becomes higher as more partitions are added.  This is
     particularly true for the <command>UPDATE</command> and
     <command>DELETE</command> commands.  Another reason to be concerned about