Add basic usage examples

README.md

@@ -0,0 +1,21 @@
+# Tracking Time
+
+To start running PunchIn for a specific client, use:
+
+```sh
+cargo run -- start <client>.json
+```
+
+Enter the projects as you start working on them. Each time you switch to a new
+project, the current project will be committed and rounded to the next chunk
+(by default, 30 minutes). Once finished, be sure to exit the program using
+ctrl-d or EOL to properly save progress.
+
+# Generating Reports
+
+PunchIn natively supports Markdown and CSV.
+
+```sh
+cargo run -- report <client>.json --format markdown --timescale hours
+cargo run -- report <client>.json --format csv --timescale hours
+```