influxdbc: docs for a couple of existing functions

src/modules/influxdbc/doc/influxdbc_admin.xml

@@ -156,6 +156,75 @@ request_route {
     ...
 }
 ...
+</programlisting>
+		</example>
+	</section>
+	<section id="influxdb.f.influxdbc_sub">
+		<title>
+		<function moreinfo="none">influxdbc_sub(name)</function>
+		</title>
+		<para>
+		Start a measure subgroup with the given name.
+		</para>
+		<para>
+		This function can be used from ANY_ROUTE.
+		</para>
+		<example>
+		<title><function>influxdbc_sub()</function> usage</title>
+		<programlisting format="linespecific">
+...
+request_route {
+    ...
+    influxdbc_sub("grp1");
+    ...
+}
+...
+</programlisting>
+		</example>
+	</section>
+	<section id="influxdb.f.influxdbc_subend">
+		<title>
+		<function moreinfo="none">influxdbc_subend()</function>
+		</title>
+		<para>
+		End the current measure subgroup.
+		</para>
+		<para>
+		This function can be used from ANY_ROUTE.
+		</para>
+		<example>
+		<title><function>influxdbc_subend()</function> usage</title>
+		<programlisting format="linespecific">
+...
+request_route {
+    ...
+    influxdbc_subend();
+    ...
+}
+...
+</programlisting>
+		</example>
+	</section>
+	<section id="influxdb.f.influxdbc_push">
+		<title>
+		<function moreinfo="none">influxdbc_push()</function>
+		</title>
+		<para>
+		Push accumulated values to the server.
+		</para>
+		<para>
+		This function can be used from ANY_ROUTE.
+		</para>
+		<example>
+		<title><function>influxdbc_push()</function> usage</title>
+		<programlisting format="linespecific">
+...
+request_route {
+    ...
+    influxdbc_push();
+    ...
+}
+...
 </programlisting>
 		</example>
 	</section>