add docs for form_header (#1027)

source/how-tos/app-development/interactive/form.rst

@@ -108,6 +108,14 @@ This is the full list of items with details, you may supply to this yaml file to
 
        whether or not the application is cacheable or not. Defaults to true.
 
+.. _bc_form_header:
+.. describe:: form_header (String)
+
+    New in 4.0.
+
+    Add a text header to the form. Note this is different from the
+    manifest's description as it does not appear as hoverover text.
+
 .. _bc_form_attributes:
 
 Attributes

source/release-notes/v4.0-release-notes.rst

@@ -17,8 +17,9 @@ New Features
 - `noVNC quality and compression defaults`_
 - `Batch connect sessions poll delay`_
 - `System Status application`_
-- `User mapping now accepts UIDs`
-- `Remove runtime dependency on SCL`
+- `User mapping now accepts UIDs`_
+- `Interactive apps can have a text header`_
+- `Remove runtime dependency on SCL`_
 
 Thanks!
 -------
@@ -338,6 +339,17 @@ User mapping scripts can now return a UID instead of a username.
 This can be helpful for centers that have multiple domains and possible
 username collisions.
 
+Interactive apps can have a text header
+.......................................
+
+The item ``form_header`` can be added to intereactive applications
+to display additional text in the form. Note this is different from
+the ``manifest.yml``'s ``description`` field becuase it will not be
+displayed on hoverover.
+
+See the :ref:`form documentation for form_header <bc_form_header>`
+for more details.
+
 Remove runtime dependency on SCL
 ................................