Doc: clean up markup for jsonb_set and related functions.

The markup for optional parameters was neither correct nor consistent.
In passing, fix a spelling mistake.

Per report from Alex Macy.  Some of these mistakes are old, so
back-patch as appropriate.

Discussion: https://postgr.es/m/156953522258.1204.12736099368284950578@wrigleys.postgresql.org

doc/src/sgml/func.sgml

@@ -12428,7 +12428,7 @@ table2-mapping
        <entry><literal>[{"f1":1},2,null,3]</literal></entry>
        </row>
       <row>
-       <entry><para><literal>jsonb_set(target jsonb, path text[], new_value jsonb<optional>, <parameter>create_missing</parameter> <type>boolean</type></optional>)</literal>
+       <entry><para><literal>jsonb_set(target jsonb, path text[], new_value jsonb <optional>, create_missing boolean</optional>)</literal>
          </para></entry>
        <entry><para><type>jsonb</type></para></entry>
        <entry>
@@ -12439,7 +12439,7 @@ table2-mapping
          <replaceable>create_missing</replaceable> is true (default is
          <literal>true</literal>) and the item
          designated by <replaceable>path</replaceable> does not exist.
-         As with the path orientated operators, negative integers that
+         As with the path oriented operators, negative integers that
          appear in <replaceable>path</replaceable> count from the end
          of JSON arrays.
        </entry>
@@ -12453,7 +12453,7 @@ table2-mapping
       <row>
        <entry>
            <para><literal>
-           jsonb_insert(target jsonb, path text[], new_value jsonb, <optional><parameter>insert_after</parameter> <type>boolean</type></optional>)
+           jsonb_insert(target jsonb, path text[], new_value jsonb <optional>, insert_after boolean</optional>)
            </literal></para>
        </entry>
        <entry><para><type>jsonb</type></para></entry>
@@ -12468,7 +12468,7 @@ table2-mapping
          designated by <replaceable>path</replaceable> is in JSONB object,
          <replaceable>new_value</replaceable> will be inserted only if
          <replaceable>target</replaceable> does not exist. As with the path
-         orientated operators, negative integers that appear in
+         oriented operators, negative integers that appear in
          <replaceable>path</replaceable> count from the end of JSON arrays.
        </entry>
        <entry>
@@ -12509,7 +12509,7 @@ table2-mapping
        <row>
         <entry>
          <para><literal>
-           jsonb_path_exists(target jsonb, path jsonpath [, vars jsonb [, silent bool]])
+           jsonb_path_exists(target jsonb, path jsonpath <optional>, vars jsonb <optional>, silent bool</optional></optional>)
          </literal></para>
         </entry>
         <entry><type>boolean</type></entry>
@@ -12529,7 +12529,7 @@ table2-mapping
        <row>
         <entry>
          <para><literal>
-           jsonb_path_match(target jsonb, path jsonpath [, vars jsonb, silent bool])
+           jsonb_path_match(target jsonb, path jsonpath <optional>, vars jsonb <optional>, silent bool</optional></optional>)
          </literal></para>
         </entry>
         <entry><type>boolean</type></entry>
@@ -12550,7 +12550,7 @@ table2-mapping
        <row>
         <entry>
          <para><literal>
-           jsonb_path_query(target jsonb, path jsonpath [, vars jsonb, silent bool])
+           jsonb_path_query(target jsonb, path jsonpath <optional>, vars jsonb <optional>, silent bool</optional></optional>)
          </literal></para>
         </entry>
         <entry><type>setof jsonb</type></entry>
@@ -12578,7 +12578,7 @@ table2-mapping
        <row>
         <entry>
          <para><literal>
-           jsonb_path_query_array(target jsonb, path jsonpath [, vars jsonb, silent bool])
+           jsonb_path_query_array(target jsonb, path jsonpath <optional>, vars jsonb <optional>, silent bool</optional></optional>)
          </literal></para>
         </entry>
         <entry><type>jsonb</type></entry>
@@ -12598,7 +12598,7 @@ table2-mapping
        <row>
         <entry>
          <para><literal>
-           jsonb_path_query_first(target jsonb, path jsonpath [, vars jsonb, silent bool])
+           jsonb_path_query_first(target jsonb, path jsonpath <optional>, vars jsonb <optional>, silent bool</optional></optional>)
          </literal></para>
         </entry>
         <entry><type>jsonb</type></entry>