Update README

Signed-off-by: mi2428 <[email protected]>

README.md

@@ -1 +1,46 @@
 # dns-query-interceptor
+Tiny program intercepting DNS queries
+
+[![asciicast](https://asciinema.org/a/431381.svg)](https://asciinema.org/a/431381?autoplay=1)
+
+## Use alone
+Golang compiler and `libpcap-dev` are needed to build - you may get the latest binary from [Releases](https://github.com/wide-vsix/dns-query-interceptor/releases).
+
+```
+% git clone --depth 1 https://github.com/wide-vsix/dns-query-interceptor
+% cd dns-query-interceptor
+% make build
+% sudo cp bin/interceptor /usr/local/bin/interceptor
+```
+
+Following options are available:
+
+```
+% interceptor -h
+-i, --dev string                Capturing interface name
+-q, --quiet                     Suppress standard output
+    --db-host string            Postgres server address to store queries (e.g., localhost:5432)
+    --db-name string            Database name to store queries
+    --db-user string            Username to login DB
+    --db-password-file string   Path of plaintext password file
+-h, --help                      Show help message
+-v, --version                   Show build version
+```
+
+## Use with PostgreSQL
+
+**CAUTION:** Defaults of this repository are for the vSIX Access Service.
+
+```
+% make install
+% sudo systemctl start [email protected]
+```
+
+Uninstall from systemd and purge the database - note that this is a destructive operation and cannot be undone.
+
+```
+% make uninstall
+```
+
+## License
+This product is licensed under [The 2-Clause BSD License](https://opensource.org/licenses/BSD-2-Clause) - see the [LICENSE](LICENSE) file for details.