nghttpx: Add description about error message when TLS protocols do not overlap
nghttpx: Add description about error message when TLS protocols do not overlap

wzyboy/nghttp2,icing/nghttp2,icing/nghttp2,icing/nghttp2,icing/nghttp2,wzyboy/nghttp2,wzyboy/nghttp2,icing/nghttp2,wzyboy/nghttp2,wzyboy/nghttp2,icing/nghttp2,wzyboy/nghttp2,wzyboy/nghttp2,icing/nghttp2