docs: rewrite project readme

Rewrite the project README file to be more succinct and to the point. Add
new section on getting started quickly with either docker or the standalone
binary file.
Update CHANGELOG file with recent changes.

CHANGELOG.md

@@ -7,6 +7,9 @@ The format is based on [Keep a Changelog], and this project adheres to [Semantic
 ## [Unreleased]
 
 ### Added
+- (23e073f) feat: add example systemd service file
+- (3911eca) feat: rename output binary and archives
+- (f6e328a) feat: correctly handle shutdown signals
 - (6e575aa) feat: rewrite cli flags and environment variables
 - (0f0efe5) feat: remove startup script from docker image
 - (e2902b8) feat: improve logging on startup
@@ -18,6 +21,7 @@ The format is based on [Keep a Changelog], and this project adheres to [Semantic
 - (93da909) fix: use correct flag in dockerfile ([#18](https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/issues/18))
 
 ### BREAKING CHANGE
+- Release binary name has been changed to `fail2ban_exporter`.
 - Replace `--socket` flag with `--collector.f2b.socket`.
 - Merge `--port` flag and `--web.listen-address` into a single flag.
 - Remove `--collector.textfile` flag, its value is now derived from `--collector.textfile.directory`.