message: Minor tweaks to the root readme
diff: ## Linux
  1) Install rust and rustup (https://www.rust-lang.org/install.html).
  2) Install libindy_1.6.1 (https://repo.sovrin.org/sdk/deb/pool/xenial/stable/libi/libindy/)
  +2) Install libnullpay_1.6.1 (https://repo.sovrin.org/sdk/deb/pool/xenial/stable/libn/libnullpay/)
  3) Clone this repo to your local machine.
  -4) From the local repository run the following commands to verify everything works:
  +4) From the sdk/vcx/libvcx folder inside this local repository run the following commands to verify everything works:
  ```
  $ cargo build
  $ cargo test
  **`libvcx_<ver>_amd.deb`**
  - a debian that will install the .so library into /usr/lib, update `ldconfig`, and install provision script to `/usr/share/libvcx/`.
  -- Published to https://repo.corp.evernym.com/deb/pool/main/libc/libvcx/
  **`vcx_<ver>.deb`**
  - an unintelligent debian package that puts the nodejs package contents into a global node_modules location.
  