Fix appearance of multi-line text variables

[sirnewton01]

The current multi-line text boxes are surrounded by code fences using the back-ticks. The textual representation is ugly and it causes escaping difficulties in the Go code.

Instead, several tildes could be used with a much better visual effect. Tildes as code fences appears to be part of the original standard and a variable number of them could be used to help and avoid escaping collisions within the descriptions.

Also, the three underscores after the block are unnecessary and waste vertical space. Instead, if there is a fenced code block the variable should be bound to the literal contents of the block. There should be no need for them in this case. They should remain for the single-line text case though as they serve as a good visual cue and it is sometimes unclear where the end of the text should be.