Add badges for crates.io and minimum rustc version

This change adds another two badges to the repository. The first simply
lists the most recent version of the crate as published on crates.io.
The second one states the minimum version of rustc that is required for
building. We have recently switched to using Rust 2018 and with that we
have a requirement for version 1.31 of the toolchain. In the future the
hope is that now that we have a proper CI/CD pipeline based off of
Docker images we should be able to build on past versions of Rust, even
if they are not used during development.

CHANGELOG.md

@@ -8,7 +8,8 @@ Unreleased
 - Enabled `unused-results` lint
 - Enabled CI pipeline comprising building, testing, and linting of the
   project
-  - Added badge indicating pipeline status
+- Added badges indicating pipeline status, current `crates.io` published
+  version of the crate, and minimum version of `rustc` required
 - Added categories to `Cargo.toml`
 
 

README.md

@@ -1,4 +1,6 @@
 [![pipeline](https://gitlab.com/d-e-s-o/notnow/badges/devel/pipeline.svg)](https://gitlab.com/d-e-s-o/notnow/commits/devel)
+[![crates.io](https://img.shields.io/crates/v/notnow.svg)](https://crates.io/crates/notnow)
+[![rustc](https://img.shields.io/badge/rustc-1.31+-blue.svg)](https://blog.rust-lang.org/2018/12/06/Rust-1.31-and-rust-2018.html)
 
 notnow
 ======
@@ -74,14 +76,10 @@ honored.
 Status
 ------
 
-The program is in a well progressed development phase. A lot of the
+**notnow** is in a well progressed development phase. A lot of the
 desired functionality exists, but not all is hooked up with the UI. More
 improvements are being worked on.
 
-**notnow** typically compiles with the most recent version of stable
-Rust. On compile errors please try upgrading to a more recent version
-first.
-
 [rust-lang]: https://www.rust-lang.org
 [rfc-4791]: https://tools.ietf.org/html/rfc4791
 [gui]: https://crates.io/crates/gui