update "information about the vCard compatibility issues"

[nutpantz]

the "information about the vCard compatibility issues" is very important
but appears to be 10 years old. have things improved?

as someone who wants to move away from big corp holding and syncing my data
i would love to know how things stand today and how the standards have improved.
or should i just "pick a app and live with never having good interoperability between OEMS like windows, linux, apple and android"

is there a newer blog post with newer info or have things just not gotten better in ten years?

[lucc]

I think this question goes to @scheibler.

If you have special compatibility problems I am open to PRs, preferably RFC conforming stuff.