No markdown docs for elements

Sphinx does not support markdown, therefore all our element docs should
not be in this format.

Change-Id: I6fceb5c2c218e94a463f13d6d9050aea485e6c31

bin/dib-lint

@@ -128,7 +128,7 @@ for i in $(find elements -type f); do
     fi
 done
 
-for i in $(find elements -type f -and -name '*.md' -or -type f -executable); do
+for i in $(find elements -type f -and -name '*.rst' -or -type f -executable); do
     # Check for tab indentation
     if ! excluded tabindent; then
         if grep -q $'^ *\t' ${i}; then
@@ -142,4 +142,9 @@ for i in $(find elements -type f -and -name '*.md' -or -type f -executable); do
         fi
     fi
 done
+
+md_docs=$(find elements -name '*.md')
+if [ -n "$md_docs" ]; then
+    error ".md docs found: $md_docs"
+fi
 exit $rc

elements/deploy-targetcli/README.rst

@@ -1,3 +1,6 @@
+deploy-targetcli
+================
+
 Use targetcli for the deploy ramdisk
 
 Provides the necessary scripts and dependencies to use targetcli

elements/deploy-tgtadm/README.rst

@@ -1,3 +1,6 @@
+deploy-tgtadm
+=============
+
 Use tgtadm and tgtd for the deploy ramdisk
 
 Provides the necessary scripts and dependencies to use tgtadm