Update README

README.md

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-CLI for fetching weather data from the [Open Weather API](https://openweathermap.org)
+# weather-cli
+
+Command line client for fetching weather data from the [Open Weather API](https://openweathermap.org).
+
+This small client uses the OpenWeather API to provide forecasts based on current location, zip code, exact 
+coordinates, and city name. In addition, the client is capable of connecting to its partner project, 
+[SimplrWeather](https://github.com/vincentmoreschi/SimplrWeather), which provides a gRPC backend for retrieving
+historical weather data.
+
+### Instructions
+
+A file named `.env` must be placed in the root of the project or in the directory from which you will run the compiled
+binary. You *must* provide a port number and an OpenWeather API key in this file:
+
+```
+API_KEY=xxxxxxxxxxxxxxxx
+PORT=xxxxx
+```
+
+Once complete, you can start the client by runnning `go run cmd/*.go` from the root of the project. Optionally, binary
+files can also be compiled with `go build`.
+
+By default, the client will automatically obtain your approximate location using your IP address. Additional data based
+on IP address is fetched from [ipinfo.io](https://ipinfo.io). If you don't want your IP address sent to that API, simply
+choose among the other options.
+
+Basic options include:
+- Automatically obtain forecast for your location
+- Search by zip code
+- Search by city name
+
+Advanced options:
+- Change units (default imperial)
+- Search with exact location (latitude and longitude)
+- Historical data
+
+#### Screenshot
+
+![Main menu](info/image.png)