doc: Update documentation of keyboard shortcuts for expand/collapse

doc: Update documentation of keyboard shortcuts for expand/collapse

Some keyboard shortcuts were added for expanding and collapsing
entries so we need to update the documentation.

See https://git.eclipse.org/r/#/c/70583/

Change-Id: I8ffdf4654e5dd7c6cbfd6bc9f95405a5495b9a49
Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/72566
Reviewed-by: Jean-Christian Kouame <jean-christian.kouame@ericsson.com>
Tested-by: Jean-Christian Kouame <jean-christian.kouame@ericsson.com>