Replace all [[srd:]] and similar style links with {{ jtl.format }} for flexibility

[eepMoody]

Within all desc fields, any instance of the old URL style [[srd:whatever]] or similar should be replaced. The standard format we want looks like:

[Plaintext Name]({{ base_url }}/endpoint/item)

Eg. [Fireball]({{ base_url }}/spells/fireball

The readme should also be updated to reflect and explain this format, which is called JTL.