Apply get_signature_algorithm parts of okuda's patch
diff --git a/doc/pyOpenSSL.tex b/doc/pyOpenSSL.tex
index 239133f..575eb8e 100644
--- a/doc/pyOpenSSL.tex
+++ b/doc/pyOpenSSL.tex
@@ -321,6 +321,10 @@
Return the certificate serial number.
\end{methoddesc}
+\begin{methoddesc}[X509]{get_signature_algorithm}{}
+Return the signature algorithem used in the certificate.
+\end{methoddesc}
+
\begin{methoddesc}[X509]{get_subject}{}
Return an X509Name object representing the subject of the certificate.
\end{methoddesc}