Description field length

[glpoulter]

The admin page tells the user this a max of 30 words, but the schema has set it to max 300 characters - potentially confusing for the user. Also might not be enough.

[glpoulter]

It's not easy (or even possible?) to change schema to only allow a certain number of words, so change admin help message to something like: "Describe your solver. Character limit (including spaces) is x, which is approximately y words"

[glpoulter]

Gone for 400 characters but might need to review this.