A TODO note for ssl-enum-ciphers

We recently became dependent on OpenSSL for some of ssl-enum-ciphers's
functionality (parsing certificates). We should have a decent fallback
(e.g. don't parse the certificate, issue a warning, and use a dummy
score).

[ci skip] This tells Travis to skip the CI build when this commit is
pushed, useful for documentation changes that don't affect the build.

scripts/ssl-enum-ciphers.nse

@@ -509,6 +509,8 @@ local function find_ciphers_group(host, port, protocol, group, scores)
                 -- This may not always be the case, so
                 -- TODO: reorder certificates and validate entire chain
                 -- TODO: certificate validation (date, self-signed, etc)
+                -- TODO: Handle this gracefully when OpenSSL is not compiled in
+                --       (throws error otherwise)
                 local c = sslcert.parse_ssl_certificate(certs.certificates[1])
                 if c.pubkey.type == kex.pubkey then
                   local sigalg = c.sig_algorithm:match("([mM][dD][245])")