HPCC-16283 Document BUILD after MERGE

Signed-off-by: Jim DeFabia <[email protected]>

docs/EN_US/ECLLanguageReference/ECLR_mods/BltInFunc-BUILD.xml

@@ -703,6 +703,15 @@ BUILD(Vehicles,SearchTerms,Payload,'vkey::st.city2');
     <programlisting>nameKey := INDEX(mainTable,{surname,forename,filepos},'name.idx');
 BUILD(nameKey); //gets all info from the INDEX definition
 </programlisting>
+
+    <para>You can also use this form to build an index based upon two MERGEd
+    indexes. To write a MERGEd index to disk, you must use the BUILD
+    action.</para>
+
+    <para>Example:</para>
+
+    <para><programlisting>BUILD(MERGE(idx1,idx2,'~idx::MergedIndex');
+</programlisting></para>
   </sect2>
 
   <sect2 id="SepIndexFromDS" role="brk">

docs/EN_US/ECLLanguageReference/ECLR_mods/BltInFunc-MERGE.xml

@@ -169,9 +169,14 @@
   <emphasis>recordsetset</emphasis>. This is particularly useful for
   incremental data updates as it allows you to merge a smaller set of new
   records into an existing large dataset or index without having to re-process
-  all the source data again. The <emphasis>recordsetset</emphasis> form makes
-  merging a variable number of datasets possible when used inside a GRAPH
-  function.</para>
+  all the source data again. </para>
+
+  <para>The <emphasis>recordsetset</emphasis> form makes merging a variable
+  number of datasets possible when used inside a GRAPH function.</para>
+
+  <para>To write a MERGEd index to disk, you must use the BUILD action.</para>
+
+  <?hard-pagebreak ?>
 
   <para>Example:</para>
 
@@ -192,4 +197,6 @@ ds4 := MERGE(SetDS,SORTED(letter,number));
 OUTPUT(ds3);
 OUTPUT(ds4);
 </programlisting>
+
+  <para>See Also: <link linkend="BUILD">BUILD</link></para>
 </sect1>