Update docs for configuring logging formats (espcially for use with ros2 launch)

[SammyRamone]

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This is PR adds additional documentation about configuring logging with ros2 launch. It is currently a draft as it will (amon other things) provide documentation for the following PRs which are at time of writing not merged yet. https://github.com/ros2/launch/pull/713 https://github.com/ros2/launch/pull/722 https://github.com/ros2/rcutils/pull/443

I moved the part about escape characters from the demo section to the main logging documentation, since I think this makes more sense to keep it in one place.

[fujitatomoya]

@SammyRamone thanks for the contribution, i will take a look at the related PRs.

[fujitatomoya]

@SammyRamone does this still need to be a draft?

[SammyRamone]

@SammyRamone does this still need to be a draft?

@fujitatomoya One of the linked PRs is not merged yet. Therefore, I don't want to merge the documentation yet.