Docs: Clarify steps how to create a remote development workspace

What does this MR do?

I followed the documentation for workspaces, and got confused after navigating into the project to create a .devfile.yaml file. Thought that Workspaces would hide in the projects menu, hidden behind a feature flag. Searched for some minutes. Apparently, the context for Your work in the main menu was missing.

This MR clarifies the steps, and breaks the creation into two steps that require a context switch:

1. the preparation with the projects .devfile.yaml
2. Switching context into a different UI to create the workspaces.

I also wanted to make sure that folks know which .devfile.yaml they should create and fill, and linked the example configuration anchor below. This is part of the 5 minute success learning curve (more to come in future MRs).

Related issues

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