Add release notes for LLDB inline diagnostics

[adrian-prantl]

No description provided.

[DavidSpickett]

LGTM, thanks!

[DavidSpickett]

I know I'm the one who asked you to release note this, but somehow I forgot about it and got this today:

(lldb) expression *(char[4])b
                   ˄˜˜˜˜˜˜˜˜
                   ╰─ error: C-style cast from 'int *' to 'char[4]' is not allowed

I was quite shocked to see the sort of diagnostics I expect from rustc, but in lldb. This is a great feature @adrian-prantl !

Definitely falls into the category of things users didn't know needed to be improved, but it's clearly an improvement once it's done.

[adrian-prantl]

Also want to make sure @PortalPete sees this, who wrote the original prototype for this and came up with the design!