Feature request: troubleshooting topics

[larrykollar]

Supporting troubleshooting topics would be a useful addition. It might work like this:

# Troubleshooting something {.troubleshooting}

optional shortdesc

## some title {.condition}

If the title is blank, use the default heading.

## some title {.cause}

ditto

## some title {.remedy}

ditto

The cause and remedy sub-sections could be repeated if necessary. If the sub-section titles are blank (for example, ## {.condition}, use the default titling for those sections.