rename PBKDF2 to PBKDF2HMAC, address many other review comments
diff --git a/docs/hazmat/primitives/key-derivation-functions.rst b/docs/hazmat/primitives/key-derivation-functions.rst
index 51d73bc..bad7a36 100644
--- a/docs/hazmat/primitives/key-derivation-functions.rst
+++ b/docs/hazmat/primitives/key-derivation-functions.rst
@@ -35,7 +35,7 @@
:class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm`
provider.
:param int length: The desired length of the derived key. Maximum is
- 2\ :sup:`31` - 1.
+ (2\ :sup:`32` - 1) * ``algorithm.digest_size``
:param bytes salt: A salt. `NIST SP 800-132`_ recommends 128-bits or
longer.
:param int iterations: The number of iterations to perform of the hash