OPenweathermap now also requires an api.key, it does no longer work reliable without one.

Add hints about this to the readme and metadata.json.

README.md

@@ -88,9 +88,8 @@ Launch *gnome-shell-extension-prefs* (reachable also through the *OpenWeather Se
 
 You can also use *dconf-editor* or *gsettings* to configure the extension through the command line.
 
-The [OpenWeatherMap](https://openweathermap.org/) maintainers recommend to use an [API key](http://openweathermap.org/appid). This key can be added in the preferences dialog.
-To use [Forecast.io](https://forecast.io) you need an to [register](https://developer.forecast.io/register) and get an API key. With this key you can make 1000 requests per day for free. This should be enough for this extension in any normal use case.
-
+On [OpenWeatherMap](https://openweathermap.org/) you have to register to get an [API key](http://openweathermap.org/appid). This key has to be added in the preferences dialog.
+To use [Forecast.io](https://forecast.io) you also need to [register](https://developer.forecast.io/register) and get an API key. With this key you can make 1000 requests per day for free. This should be enough for this extension in any normal use case. Do not add billing information, otherwise you might have to pay for the weather-data if something went wrong !
 ----
 
 # Licence

data/metadata.json.in

@@ -1,7 +1,7 @@
 {
 "uuid": "@uuid@",
 "name": "OpenWeather",
-"description": "Weather extension to display weather information from https://openweathermap.org/ or https://forecast.io for almost all locations in the world.\nTo use the weather-data of forecast.io, you have to register on their site (https://developer.forecast.io/register) and get a personal API-key.\n\nSince version 29 this extensions uses coordinates to store the locations and makes the names editable to support multiple weather-providers!\nIf you update from versions prior to 29 to 29 or greater (with forecast.io - support) you have to recreate your locations.",
+"description": "Weather extension to display weather information from https://openweathermap.org/ or https://forecast.io for almost all locations in the world.\nYou have to register on the respective site (either http://openweathermap.org/appid or https://developer.forecast.io/register) and get a personal API-key.\n\nSince version 29 this extensions uses coordinates to store the locations and makes the names editable to support multiple weather-providers!\nIf you update from versions prior to 29 to 29 or greater (with forecast.io - support) you have to recreate your locations.",
 "shell-version": [ "3.12", "3.14", "3.16", "3.17.4", "3.17.90", "3.17.91", "3.17.92", "3.18" ],
 "localedir": "@LOCALEDIR@",
 "url": "@url@",