TODO items related to consensus

[olemis]

• docs/skycoin/_data/devdocs/en/guides/block_chain.md:186:TODO: Document block height and forking
• docs/skycoin/_data/devdocs/en/guides/block_chain.md:260:TODO: Document changes in consensus rules
• docs/skycoin/_data/devdocs/en/guides/block_chain.md:269:TODO: Document fork detection
• docs/skycoin/_data/devdocs/en/guides/p2p_network.md:83:TODO: Look for equivalents of Bitcoin's 11 seconds rule in Skycoin Core
• docs/skycoin/_data/devdocs/en/guides/p2p_network.md:208:TODO: At this point forks might become evident, include in docs
• docs/skycoin/_data/devdocs/en/guides/p2p_network.md:413:TODO: Come back to this when we have consensus

Resolve these TODO items once consensus will be implemented .