message: docs(readme): fix broken links: build status, build guide, etc.
diff: @@ -41,7 +41,7 @@ There is also a great [sandbox](https://katacoda.com/hyperledger-iroha/scenarios
  ### How to build Iroha?
  -Use [build guide](https://iroha.readthedocs.io/en/master/build/index.html), which might be helpful if you want to modify the code and contribute.
  +Use [build guide](https://iroha.readthedocs.io/en/main/build/index.html), which might be helpful if you want to modify the code and contribute.
  ### Is there SDK available?
  @@ -62,7 +62,7 @@ It is based on JS Wallet but is up-to-date.
  ### Want to help us develop Iroha?
  That's great!
  -Check out [this document](https://github.com/hyperledger/iroha/blob/master/CONTRIBUTING.rst)
  +Check out [this document](https://github.com/hyperledger/iroha/blob/main/CONTRIBUTING.rst)
  ## Need help?
  