added self-hosting guide

Dockerfile

@@ -6,4 +6,5 @@ COPY . .
 RUN npm run generate
 
 FROM nginx:alpine
-COPY --from=build /app/public /usr/share/nginx/html
+COPY --from=build /app/public /usr/share/nginx/html
+EXPOSE 80

README.md

@@ -60,6 +60,19 @@ You can,
 - Logo and some icons by [Vishnu Raghav](https://www.vishnuraghav.com/)
 - [QRCode-SVG](https://github.com/papnkukn/qrcode-svg)
 
+## Self-Hosting Guide - Docker
+
+In order to quickly host the EnBizCard Generator on a machine running Docker and Docker Compose, follow these steps:
+
+1. Create a .env file by copying and adjusting env.example:
+
+```
+cp env.example .env
+```
+
+2. Run `docker-compose up -d`
+3. Access the app at http://localhost:22212 (or a different port, in case you edited the .env file).
+
 ## License
 
 ```
@@ -78,6 +91,7 @@ GNU Affero General Public License for more details.
 
 You should have received a copy of the GNU Affero General Public License
 along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 ```
 
 ## Support me

docker-compose.yml

@@ -4,5 +4,5 @@ services:
     build: .
     container_name: enbizcard
     ports:
-      - 80:80
+      - ${ENBIZCARD_PORT}:80
     restart: always

env.example

@@ -0,0 +1 @@
+ENBIZCARD_PORT:22212