Fix and update data on bitinfocharts.com

[xaur]

https://bitinfocharts.com/decred/

First, there is some wrong data:

• GitHub stars tracks wrong repo (decred-release)
• GitHub last commit tracks wrong repo
• GitHub release is v1.3.0 and not v1.3.1 (and need to be updated to 1.4

Second, there's a ton of interesting metrics that can be added: blockchain size, active addresses, hashrate, etc etc. See Bitcoin for example.

[xaur]

Release now points to v1.4 but the repository still need to be changed to dcrd