docs: Added CLI usage instructions

README.md

@@ -122,6 +122,38 @@ default, the auto-generated links are adjective-name pairs. You can use UIDs by
 the `slug_style` variable to `UID`. You can also set the length of those slug by setting
 the `slug_length` variable. It defaults to 8, and a minimum of 4 is supported.
 
+## CLI usage instructions
+The application can be used from the terminal using something like `curl`. In all the examples
+below, replace `http://localhost:4567` with where your instance of `chhoto-url` is accessible.
+
+If you have set up
+a password, first do the following to get an authentication cookie and store it in a file.
+```bash
+curl -X post -d "<your-password>" -c cookie.txt http://localhost:4567/api/login
+```
+You should receive "Correct password!" in case the provided password was correct. For any other
+request, please add `-b cookie.txt` to use this authentication cookie.
+
+To add a link, do
+```bash
+curl -X POST -d '{"shhortlink":"<shortlink>", "longlink":<longlink>}' http://localhost:4567/api/new
+```
+Send an empty `<shortlink>` if you want it to be auto-generated. The server will reply with the generated shortlink.
+
+To get a list of all the currently available links as `json`, do
+```bash
+curl http://localhost:4567/api/all
+```
+
+To delete a link, do
+```bash
+curl -X DELETE http://localhost:4567/api/del/<shortlink>
+```
+The server will send a confirmation.
+
+You can get the version of `chhoto-url` the server is running using `curl http://localhost:4567/api/version` and
+get the siteurl using `curl http://localhost:4567/api/siteurl`.
+
 ## Disable authentication
 If you do not define a password environment variable when starting the docker image, authentication
 will be disabled.