[clang] Docs: ambiguous use of "explicitly" in [[clang::no_specializaiton]] (PR #143839)

[A. Jiang via cfe-commits]

frederick-vs-ja wrote:

If we choose to be consistent with the standard wording, we might need to say "[...] templates for which neither explicit specialization nor partial specialization should be declared [...]", which is quite verbose.

The crux seems to be that it's not clear in the standard wording what's meant by saying "a program (user code) specializes a template".

https://github.com/llvm/llvm-project/pull/143839