docs: fix ui links to tedge-container-plugin-ui repository

[reubenmiller]

Fix some broken links refering to the Cumulocity UI extension.

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
32	0	0	32	100	6m55.228975s

Passed Tests

Name	⏱️ Duration	Suite
Get Container Logs	5.499 s	Container-Logs
Get Container Logs with only last N lines	0.545 s	Container-Logs
Remove Container	6.902 s	Container-Remove
Remove Container Non Existent Container Should Not Through An Error	0.060 s	Container-Remove
Restart Container	0.493 s	Container-Restart
Restart Unknown Container Fails	0.077 s	Container-Restart
Update to tedge-container-plugin-ng	24.327 s	Installation
Check for Update	6.701 s	Operations-Clone
Clone Existing Container	25.292 s	Operations-Clone
Clone Existing Container by Timeout Whilst Waiting For Exit	17.897 s	Operations-Clone
Clone Existing Container but Waiting For Exit	25.268 s	Operations-Clone
Ignore Containers With Given Label	20.989 s	Operations-Clone
Install/uninstall container package from private repository - credentials file	13.574 s	Operations-Private-Registries
Install/uninstall container package from private repository - credentials script	13.504 s	Operations-Private-Registries
Install/uninstall container package from private repository - credentials script with cache	20.438 s	Operations-Private-Registries
Install/uninstall container package from private repository - engine credentials	14.915 s	Operations-Private-Registries
Install/uninstall container package from private repository - docker from docker	35.429 s	Operations-Private-Registries
Get Configuration	5.003 s	Operations
Install/uninstall container-group package	14.262 s	Operations
Install invalid container-group	2.775 s	Operations
Install container-group with multiple files - app1	11.675 s	Operations
Install container-group with multiple files - app2	7.462 s	Operations
Install/uninstall container package	12.050 s	Operations
Install/uninstall container package from file	8.883 s	Operations
Manual container creation/deletion	15.009 s	Operations
Manual container creation/deletion with error on run	7.376 s	Operations
Manual container created and then killed	9.761 s	Operations
Self Update Is Present Using Self Type	0.152 s	Self
Self Update Is Present Using Container Type	0.149 s	Self
Self Update Is Not Present	0.152 s	Self
Service status	17.756 s	Telemetry-Main
Sends measurements	70.854 s	Telemetry-Main