feat: Add icon for refinement params that explains what they are

[cadenmyers13]

Problem

When new users are getting into pdf fitting, the fitting parameters seem physically meaningless (delta2, sratio, etc).

Proposed solution

Add a small info icon next to each parameter that briefly explains what it is, whether it relates to structural or instrument, and if its refineable ("refineability" is nuanced, sometimes you always refine like a,b,c while other times they come from the instrument like qdamp). Example of what these could be are shown in tables in diffpy.cmi docs: https://www.diffpy.org/diffpy.cmi/tutorials/index.html#structural-parameters