build: minimal doc in README

Put minima build instructions in top-level README.

Signed-off-by: Shachar Sharon <[email protected]>

Author: synarete

README.md

@@ -1 +1,13 @@
-# Smb Metrics
+# Samba Metrics
+
+Samba metrics exporter converts 'smbstatus' output into
+[Prometheus](https://prometheus.io/)
+[data-model](https://prometheus.io/docs/concepts/data_model/) metrics format.
+
+## Build
+
+```bash
+$ make build
+
+$ make image
+```