[network-spec] Fix dead links
[network-spec] Fix dead links

In conversion to Github, the links were not updated to the appropriate
docs.

Resolves https://github.com/diem/diem/issues/8521

Closes: #8540

aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,libra/libra