Update README: Correct environment variable (PORT) passed to the cont…

…ainer.

README.md

@@ -268,12 +268,12 @@ Run the following Docker command to run the hplip-printer-app image:
   sudo docker run --rm -d \
       --name hplip-printer-app \
       --network host \
-      -e PORT:<port> \
+      -e PORT=<port> \
       openprinting/hplip-printer-app:latest
 ```
 - `PORT` is an optional environment variable used to start the printer-app on a specified port. If not provided, it will start on the default port 8000 or, if port 8000 is busy, on 8001 and so on.
 - **The container must be started in `--network host` mode** to allow the Printer-Application instance inside the container to access and discover printers available in the local network where the host system is in.
-- Alternatively using the internal network of the Docker instance (`-p <port>:8000` instead of `--network host -e PORT:<port>`) only gives access to local printers running on the host system itself.
+- Alternatively using the internal network of the Docker instance (`-p <port>:8000` instead of `--network host -e PORT=<port>`) only gives access to local printers running on the host system itself.
 
 ### Setting Up and Running hplip-printer-app locally
 
@@ -317,12 +317,12 @@ Once the rock is built, you need to compile docker image from it.
   sudo docker run --rm -d \
       --name hplip-printer-app \
       --network host \
-      -e PORT:<port> \
+      -e PORT=<port> \
       hplip-printer-app:latest
 ```
 - `PORT` is an optional environment variable used to start the printer-app on a specified port. If not provided, it will start on the default port 8000 or, if port 8000 is busy, on 8001 and so on.
 - **The container must be started in `--network host` mode** to allow the Printer-Application instance inside the container to access and discover printers available in the local network where the host system is in.
-- Alternatively using the internal network of the Docker instance (`-p <port>:8000` instead of `--network host -e PORT:<port>`) only gives access to local printers running on the host system itself.
+- Alternatively using the internal network of the Docker instance (`-p <port>:8000` instead of `--network host -e PORT=<port>`) only gives access to local printers running on the host system itself.
 
 #### Setting up