remove rationale comment for HACL* MD5

In this commit, we move the rationale for using HACL*-based MD5
instead of its OpenSSL implementation from the code to this note.

HACL*-based MD5 is 2x faster than its OpenSSL implementation for
creating the hash object via `h = md5(..., usedforsecurity=False)`
but `h.digest()` is slightly (yet noticeably) slower.

Overall, HACL*-based MD5 still remains faster than its OpenSSL-based
implementation, whence the choice of `_md5.md5` over `hashlib.md5`.

Author: picnixz

Lib/uuid.py

@@ -728,8 +728,6 @@ def uuid3(namespace, name):
     """Generate a UUID from the MD5 hash of a namespace UUID and a name."""
     if isinstance(name, str):
         name = bytes(name, "utf-8")
-    # HACL*-based MD5 is slightly faster than its OpenSSL version,
-    # and 'import X; X.Y' is slightly faster than 'from X import Y'.
     import _md5
     h = _md5.md5(namespace.bytes + name, usedforsecurity=False)
     assert len(h.digest()) == 16