Add Specifying The Server Port as a phoenix til

phoenix/specifying-the-server-port.md

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+# Specifying The Server Port
+
+Running `mix phx.server` for a Phoenix project with the default settings
+will attach the server to port `4000`.
+
+If you'd like to use a different port in development, you can change it in
+`config/dev.exs`.
+
+```elixir
+config :profilex, Profilex.Web.Endpoint,
+  http: [port: 4444],
+  ...
+```
+
+Alternatively, you can allow it to be configurable from the command line
+with an environment variable and a fallback port.
+
+```elixir
+config :profilex, Profilex.Web.Endpoint,
+  http: [port: System.get_env("PORT") || 4000],
+  ...
+```
+
+Running
+
+```bash
+$ PORT=4444 mix phx.server
+```
+
+will launch the server on port `4444`.