[clang] [clang][analyzer] Improve documentation of checker 'cplusplus.Move' (NFC) (PR #96295)

[Balázs Kéri via cfe-commits]

balazske wrote:

I fixed a test that contained the entire option help description. I think this is not needed, removed it and only included the first line of the description.

https://github.com/llvm/llvm-project/pull/96295