Fix Opengraph and Twitter tags

Added <meta property="og:url">, <meta property="twitter:description"> and <meta property="twitter:image"> tags as they were missing.

Fixed <meta property="twitter:site"> as it was broken

Marking up content on Bisq website can:

Lead to the generation of rich snippets in search engine results like the one showed on top
Enhance CTR (Click Through Rate) from the search result
Provide greater information to search engines to improve their understanding of the content on Bisq website

bisq-network / bisq-website