Add note about compressed svg's when hitting level 4 file size limit

[bloodearnest]

We currently allow .svg file formats.

However, these are uncompressed, so even simple svg diagrams might easily go over the level 4 file limit.

In the check for L4 file size, if the file is over the limit, and is a .svg, we could potentially add guidance to recommend comporessing your svg, possibly with links to examples on how to do that in R/python/stata