Merge pull request #390 from indigoid/readme-escaping-note

brief note about escaping braces in manifests

manifests/README.rst

@@ -21,6 +21,10 @@ setting. Not all settings support this though, to see whether embedding
 a manifest variable in a setting is possible, look for the
 ``manifest vars`` label.
 
+To insert a literal ``{foo}`` use double braces, that is ``{{foo}}``.
+For example in a shell command where you may want to use the
+expression ``${foo}``, use ``${{foo}}`` instead.
+
 Sections
 --------