Document some of the methods of HasKeybindings

We have some documentation for the corresponding setters in IBaseContext, but
that's part of the controller infrastructure and not client facing. For somebody
implementing a new view, this is where they will probably look for what methods
they can override.

pkg/gui/types/context.go

@@ -246,7 +246,13 @@ type (
 type HasKeybindings interface {
 	GetKeybindings(opts KeybindingsOpts) []*Binding
 	GetMouseKeybindings(opts KeybindingsOpts) []*gocui.ViewMouseBinding
+
+	// Implement this to get called when there's a double-click on the view. Only supported by list
+	// views currently. Will be called after the double-clicked list entry has been selected.
 	GetOnDoubleClick() func() error
+
+	// Implement this in a side-panel controller to get called when there's a click in the main view
+	// that belongs to your panel while the main view is already focused.
 	GetOnClickFocusedMainView() func(mainViewName string, clickedLineIdx int) error
 }