Removal of Fuhon network implementation

[kaitlin-beegle]

Last week, the Filecoin Foundation formally suspended work on the Fuhon (C++) network implementation. The existing code repositories will remain public, but shall be unmaintained.

The updated spec should only make reference to the three actively maintained implementations (Forest, Venus, Lotus), and include a caveat indicating the existence of the C++ repos. It is important that we maintain a record of the existence of these repos, even if there are no current plans to resume work on any C++ implementation.

[kaitlin-beegle]

(Also, I believe that opening this issue is the proper protocol, but let me know if you'd prefer I go ahead push changes in a PR!)

[web3jenks]

@kaitlin-beegle this is going to be address in PR #1303

[smagdali]

Yes, we can republish on specs now!