Issue #2989998 by saphemmy: Improve Documentation on adding geocoder-php Providers

* [Drush](http://drush.org), to enable the module (and its dependencies) from

  the shell;

* The external [Geocoder Provider(s)](https://packagist.org/providers/geocoder-php/provider-implementation)

  that should enabled and used in the module. Dependant [willdurand/geocoder](https://packagist.org/packages/willdurand/geocoder)

  and (specific provider) additional / required libraries will be downloaded automatically via composer.

  that should enabled and used in the module.

  Dependant [willdurand/geocoder](https://packagist.org/packages/willdurand/geocoder)

  and (specific provider) additional / required libraries will be downloaded

  automatically via composer.

* The embedded "Geocoder Geofield" submodule requires the [Geofield

  Module](https://www.drupal.org/project/geofield);

* The embedded "Geocoder Address" submodule requires the [Address

 * "computed_string" (with "computed_field" module enabled);

 * "computed_string_long" (with "computed_field" module enabled);

 * "address" (with "address" module and "geocoder_address" sub-module enabled);

 * "address_country" (with "address" module and "geocoder_address" sub-module enabled);

 * "address_country" (with "address" module and "geocoder_address" sub-module

    enabled);

###### for Reverse Geocode operations:

 * "geofield" (with "geofield" module and "geocoder_geofield" sub-module enabled);

 * "geofield" (with "geofield" module and "geocoder_geofield" sub-module

    enabled);

**Note:** Geocoder Field sub-module provides hooks to alter (change and extend) the list of Geocoding and Reverse Geocoding fields types

**Note:** Geocoder Field sub-module provides hooks to alter (change and extend)

          the list of Geocoding and Reverse Geocoding fields types

(@see geocoder_field.api)

####Using Geocoder operations behind Proxy

$providers = \Drupal::entityTypeManager()->getStorage('geocoder_provider')->loadMultiple($provider_ids);

$addressCollection = \Drupal::service('geocoder')->geocode($address, $providers);

$addressCollection = \Drupal::service('geocoder')

->geocode($address, $providers);

```

####Note

$providers = \Drupal::entityTypeManager()->getStorage('geocoder_provider')->loadMultiple($provider_ids);

$addressCollection = \Drupal::service('geocoder')->reverse($lat, $lon, $providers);

$addressCollection = \Drupal::service('geocoder')

->reverse($lat, $lon, $providers);

```

## Return format

$providers = \Drupal::entityTypeManager()->getStorage('geocoder_provider')->loadMultiple($provider_ids);

$addressCollection = \Drupal::service('geocoder')->geocode($address, $providers);

$addressCollection = \Drupal::service('geocoder')

->geocode($address, $providers);

$address_array = $addressCollection->first()->toArray();

// You can play a bit more with the API

$addressCollection = \Drupal::service('geocoder')->geocode($address, $providers);

$addressCollection = \Drupal::service('geocoder')

->geocode($address, $providers);

$latitude = $addressCollection->first()->getCoordinates()->getLatitude();

$longitude = $addressCollection->first()->getCoordinates()->getLongitude();

```

$providers = \Drupal::entityTypeManager()->getStorage('geocoder_provider')->loadMultiple($provider_ids);

$addressCollection = \Drupal::service('geocoder')->geocode($address, $providers);

$addressCollection = \Drupal::service('geocoder')

->geocode($address, $providers);

$geojson = \Drupal::service('plugin.manager.geocoder.dumper')->createInstance('geojson')->dump($addressCollection->first());

```

$providers = \Drupal::entityTypeManager()->getStorage('geocoder_provider')->loadMultiple($provider_ids);

$addressCollection = \Drupal::service('geocoder')->geocode($address, $providers);

$addressCollection = \Drupal::service('geocoder')

->geocode($address, $providers);

$geometry = \Drupal::service('plugin.manager.geocoder.dumper')->createInstance('geometry')->dump($addressCollection->first());

```

##Geocoder API Url Endpoints

  #####Query Parameters:

  - **address** (required): The Address string to geocode (the more detailed and

  extended the better possible results.

  - **address** (required): The Address string to geocode (the more detailed

  and extended the better possible results.

  - **geocoder** (required): The Geocoder id, or a list of geocoders id separated by a comma

    (,) that should process the request (in order of priority). At least one

    should be provided. Each id should correspond with a valid @GeocoderProvider

    plugin id.

  - **geocoder** (required): The Geocoder id, or a list of geocoders id

  separated by a comma (,) that should process the request (in order of

  priority). At least one should be provided. Each id should correspond with a

  valid @GeocoderProvider plugin id.

    Note: (if not differently specified in the "options") the Geocoder

    configurations ('/admin/config/system/geocoder') will be used for each

- #### Reverse Geocode

  This endpoint allows to process a Reverse Geocode operation (get an Address

  from Geo Coordinates) on the basis of an input string of Latitude and Longitude

  coordinates, the operational Geocoder Providers and an (optional) output Format

  (Dumper).

  from Geo Coordinates) on the basis of an input string of Latitude and

  Longitude

  coordinates, the operational Geocoder Providers and an (optional) output

  Format (Dumper).

  Path: **'/geocoder/api/reverse_geocode'**

  Method: **GET**

The old signature:

```

public function reverse($latitude, $longitude, array $plugins, array $options = []);

public function reverse($latitude, $longitude,

array $plugins,

array $options = []

);

```

Since the configuration is now stored in config entities this method now takes

The new signature:

```

public function reverse(string $latitude, string $longitude, array $providers): ?AddressCollection;

public function reverse(string $latitude,

string $longitude,

array $providers): ?AddressCollection;

```

### Functional changes