Add basic example for adjusting column width draggable handle
Add basic example for adjusting column width draggable handle

Summary:
Useful for applications in wide mode that use a first page as "sidebar"
to the second page, as shown in the Simple Chat example, which this
technique combines well with.

Reviewers: mart

Subscribers: plasma-devel

Tags: #kirigami

Differential Revision: https://phabricator.kde.org/D7555

bearsh/kirigami,bearsh/kirigami