[dedicated-3.7] add documentation for template.openshift.io/bindable

(cherry picked from commit 4a84686) xref:"openshift#6206"

Author: Jim Minter

dev_guide/templates.adoc

@@ -633,6 +633,19 @@ namespace the parameter substitution resolved the value to, assuming the user
 has permission to create objects in that namespace.
 ====
 
+[[writing-marking-templates-as-bindable]]
+
+=== Marking Templates as Bindable
+
+The template service broker advertises one service in its catalog for each
+Template object that it is aware of.  By default, each of these services is
+advertised as being "bindable", i.e. an end user is permitted to bind against
+the provisioned service.
+
+Template authors can prevent end users from binding against services provisioned
+from a given Template by adding the annotation
+`template.openshift.io/bindable: "false"` to the Template.
+
 [[writing-exposing-object-fields]]
 
 === Exposing Object Fields