Allow links to be attached to descriptions

[stevejpurves]

For both tagged blocks and options, being able to provide links to further information on the publisher site would be very helpful.

An example is the description for the AGU Availability Statement tagged block which would be much better if we could provide clickable links to the appropriate resources.

AGU requires an Availability Statement for the underlying data needed to understand, evaluate, and build upon the reported research at the time of peer review and publication. Additionally, authors should include an Availability Statement for the software that has a significant impact on the research. Details and templates are in the Availability Statement section of the Data & Software for Authors Guidance:
https://www.agu.org/Publish-with-AGU/Publish/Author-Resources/Data-and-Software-for-Authors#availability
For physical samples, use the IGSN persistent identifier, see the International Geo Sample Numbers section:
https://www.agu.org/Publish-with-AGU/Publish/Author-Resources/Data-and-Software-for-Authors#IGSN

related issue: curvenote/templates#44

[rowanc1]

Would moving to markdown (common mark) help here?

[stevejpurves]

it would! good point.