Link to 3rd-part tools

[larseggert]

README currently says:

Currently supported labels as of 1.3.9:

goat, ditaa: ASCII (plaintext) art to figure conversion mscgen: Message Sequence Charts plantuml: widely used multi-purpose diagram generator plantuml-utxt: Like plantuml, except that a plantuml-generated plaintext form is used mermaid: Very experimental; the conversion to SVG is prone to generate black-on-black text in this version

Could you add links to these tools? Googling "goat svg" or "mermaid svg" is not exactly returning useful hits.

Also, "math" is missing from the list.

[larseggert]

ditaa seems to be https://github.com/stathissideris/ditaa now

[cabo]

Thanks! Fixed.