Approach for handling ADRs specific to the Rust implementation

[thanethomson]

In light of recent discussions regarding the spec and ADR processes for Tendermint, would it make sense to have a docs or adr folder in the tendermint-rs repo to allow us to discuss and record architectural decisions specific to the Rust implementation?

An example of what would require such an ADR: in implementing a reactor-style model in a similar manner to the Go version of Tendermint, should we roll our own again or should we make use of some kind of Tokio-based framework such as Actix? And if we go with a framework, how do we create/design/document some kind of interface to it that doesn't lock us into using that particular framework?

[greg-szabo]

Let's do this in our new directory structure on the new repository. I'm closing this and referencing #7 so we remember.