DOC-2578: New onSetup function for context forms. (#3550)

* DOC-2578: New onSetup function for context forms.

* Update modules/ROOT/pages/7.6.0-release-notes.adoc

Author: kemister85

modules/ROOT/pages/7.6.0-release-notes.adoc

@@ -297,6 +297,13 @@ For more information on the `+disabled+` option, see xref:editor-important-optio
 
 // CCFR here.
 
+=== New `onSetup` function for context forms
+// #TINY-11494
+
+A new `+onSetup+` API has been introduced for context forms, enabling integrators to execute a function when the form is rendered and handle cleanup when it is closed. This enhancement addresses the previous limitation of not being able to detect or trigger actions during the lifecycle of context forms. The `+onSetup+` API streamlines lifecycle management by supporting initialization at form rendering and providing a return function for cleanup, enhancing integration with plugins and applications.
+
+For more details, refer to xref:contextform.adoc#form[Context Form].
+
 === Added placeholder support for context form input fields
 // #TINY-11459
 

modules/ROOT/pages/contextform.adoc

@@ -46,6 +46,11 @@ This relates to the form itself. The form specifications are:
 |`+position+` |This controls where the context toolbar will appear with regards to the current cursor.
 |`+scope+` |This controls whether the predicate (condition) is a `+node+`-based predicate, or an `+editor+`-based predicate. See context toolbar priority for more details.
 |`+commands+` |This is a list of the items to show in the context form. They can be either `+contextformbutton+` or `+contextformtogglebutton+`.
+|`+onSetup+`
+a|
+`+(ContextFormApi) => (ContextFormApi) => void+` 
+
+Optional default: `+() => () => {}+` - Function that's  executed when the form is rendered. Once rendered It returns a function that is executed when the context form is closed.
 |===
 
 include::partial$context/positioning.adoc[leveloffset=+1]