Documentation for creating subagents and skills does not match the current portal UI

**SUMMARY**

The documentation for creating subagents and skills describes an earlier version of the Azure SRE Agent UI. The navigation path it gives does not exist in the product today, and several fields that are required to complete the task are not documented at all. Anyone following the articles step by step may not finish the task.

**SUGGESTED FIX**

Update the navigation to Builder > Agent Canvas > "+ Create subagent" / "+ Create skill".

https://learn.microsoft.com/en-us/azure/sre-agent/create-skill
https://learn.microsoft.com/en-us/azure/sre-agent/create-subagent

Start with the two linked articles, create-skill and create-subagent, and compare their navigation steps with the current Azure SRE Agent portal. Update both articles to use Builder > Agent Canvas > "+ Create subagent" / "+ Create skill", then document the required fields needed to complete each task and verify the instructions end to end.

Written by the indexing model from the issue text.