feat: add README.md (#9)

README.md

@@ -0,0 +1,33 @@
+# lubimyczytacrss
+
+lubimyczytacrss is an RSS feed generator for [lubimyczytac.pl](https://lubimyczytac.pl).
+
+## How to use?
+
+### Option 1: Use Docker
+
+```shell
+$ docker run -d \
+  -p 9234:9234 \
+  --name lubimyczytacrss \
+  kichiyaki/lubimyczytacrss:latest
+```
+Or via docker-compose:
+```yaml
+version: "3.6"
+
+services:
+  lubimyczytacrss:
+    image: kichiyaki/lubimyczytacrss:latest
+    restart: unless-stopped
+    ports:
+      - '9234:9234'
+    networks:
+      - default
+```
+
+## Available endpoints
+
+### GET /api/v1/rss/authors/{authorID}
+
+Returns an RSS feed of the newest books written by an author with a given ID and added to [lubimyczytac.pl](https://lubimyczytac.pl).