Users of FDM can update to FiniteDifferences

[nickrobinson251]

We should add the following advice to the README?

• We renamed the package for discoverability
• Turns out to rename it we had to actually register it as a new package (with a new UUID)...
• This means the old FDM URL redirects here. Packages dependening of FDM will not be affected. But all future updates will be to FiniteDifferences (not FDM).
• As far as i can tell, functionally this new package has no breaking changes from the last FDM release (counting Check that the derivative is nonnegative, and handle the case q == 0 #34 as a bug-fix)
• User can safely update their Project.toml files from

[deps]
FDM = "e25cca7e-83ef-51fa-be6c-dfe2a3123128"
...

[compat]
FDM = "0.6"

to

[deps]
FiniteDifferences = "26cc04aa-876d-5657-8c51-4c34ba976000"
...

[compat]
FiniteDifferences = "0.7"

[nickrobinson251]

need the package to be registered first JuliaRegistries/General#2535

[nickrobinson251]

Added a note to the README (#38). It just links to this issue which has all the info at the top ^^^

Let's leave the issue open for now - so people can find it and in case people have questions on updating - but I don't think anything else needs doing here :)

[oxinabox]

I think we can now close this