DOC: Fix typos in README and CONTRIBUTING

Few typos detected by misspell in the README and CONTRIBUTING.
Even if one of them is on a listing of commits. I'm assuming that
if we want to enforce less typos in the commits, having one in the
contributing guide is not the best example.
diff --git a/CONTRIBUTING b/CONTRIBUTING
index 575e63b..f217e9d 100644
--- a/CONTRIBUTING
+++ b/CONTRIBUTING
@@ -429,7 +429,7 @@
        $ git log --oneline 827752e.. | grep 'BUG\|DOC'
        0d79cf6 DOC: fix function name
        bc96534 DOC: ssl: missing LF
-       10ec214 BUG/MEDIUM: lua: the lua fucntion Channel:close() causes a segf
+       10ec214 BUG/MEDIUM: lua: the lua function Channel:close() causes a segf
        bdc97a8 BUG/MEDIUM: lua: outgoing connection was broken since 1.6-dev2
        ba56d9c DOC: mention support for RFC 5077 TLS Ticket extension in start
        f1650a8 DOC: clarify some points about SSL and the proxy protocol