doc: Fix some typos and grammar

Author: Ekaterina Kiryanova, Elena Indrupskaya, Oleg Sibiryakov, Maxim
Yablokov
Discussion: https://postgr.es/m/7aad518b-3e6d-47f3-9184-b1d69cb412e7@postgrespro.ru
Backpatch-through: 11

doc/src/sgml/ref/create_foreign_table.sgml

@@ -376,7 +376,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     an <command>UPDATE</command> that changes the partition key value can
     cause a row to be moved from a local partition to a foreign-table
     partition, provided the foreign data wrapper supports tuple routing.
-    However it is not currently possible to move a row from a
+    However, it is not currently possible to move a row from a
     foreign-table partition to another partition.
     An <command>UPDATE</command> that would require doing that will fail
     due to the partitioning constraint, assuming that that is properly