Update official doc. page

[bloxster]

• updated README with contributing instructions
• Introduction: updated and introduced Github link for contributing, introduced link to Known Issues
• Software requirements: removed detailed code instructions in for installing Go Language (not working on some platform)
• Updated Disk Space Required chapter with Chiado testnet (Amoy coming soon)
• Optmizing Storage: corrected folder denomination and level
• Default Ports and Firewalls: replaced port section with link to README and introduced Command-Line Switches for Network and Port Configuration section
• created Staking section with External CL and Caplin
• added Running an Op-node section
• clarified RPC daemon section, added The trace module subchapter
• other minor fixes