Fix some links and markup
diff --git a/src/OpenSSL/crypto.py b/src/OpenSSL/crypto.py
index 13b328f..2cb3cbd 100644
--- a/src/OpenSSL/crypto.py
+++ b/src/OpenSSL/crypto.py
@@ -635,8 +635,7 @@
"""
Initializes an X509 extension.
- :param type_name: The name of the type of extension to create. See
- http://openssl.org/docs/apps/x509v3_config.html#STANDARD_EXTENSIONS
+ :param type_name: The name of the type of extension_ to create.
:type type_name: :py:data:`bytes`
:param bool critical: A flag indicating whether this is a critical
@@ -650,6 +649,9 @@
:param issuer: Optional X509 certificate to use as issuer.
:type issuer: :py:class:`X509`
+
+ .. _extension: https://openssl.org/docs/manmaster/apps/
+ x509v3_config.html#STANDARD-EXTENSIONS
"""
ctx = _ffi.new("X509V3_CTX*")