Container debugging doc erroneously implies launch config alone will work

[bwateratmsft]

This doc sort of implies that you can copy and paste the launch config and have a working debugging experience, but this is not the case. You need to use the commands Docker: Add Dockerfiles to workspace or if Dockerfiles are added already, Docker: Initialize for debugging.

For example, copying the launch config for Python (without the tasks that are also needed) results in a cryptic error: microsoft/vscode-docker#2077

We should add text indicating that these commands are necessary, and either remove the examples or make it more clear that they alone are not enough.

[bwateratmsft]

I can't assign him but I believe @ucheNkadiCode is the right person to fix this. 😄

[gregvanl]

Assigning to @ghogen to work with @ucheNkadiCode on updating that topic.

[ucheNkadiCode]

This is now being handled in #3816

[gregvanl]

Fixed with ab31f64