Promote Search SDK as a replacement of Geocoder (#1342)

Search SDK for Android now is the recommended way to access Geocoding API on Android platform.
To promote Search SDK usage this PR:
1) Adds `Geocoder` deprecation note;
2) Assigns `services-geocoding` ownership to Search SDK Android team

Author: Nikita Novik

CODEOWNERS.md

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+# Transfer ownership over Geocoder related files to Search SDK Android team
+services-geocoding/ @mapbox/search-sdk-android

services-geocoding/README.md

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+# Geocoder
+
+[The Mapbox Search SDK for Android](https://docs.mapbox.com/android/search/guides/) is the recommended way to access the [Mapbox Geocoding API](https://docs.mapbox.com/api/search/geocoding/) on the Android platform. If you've used `Geocoder` to integrate search functionality into an Android application, you should switch to Search SDK using the [Migrate from Geocoder](https://docs.mapbox.com/android/search/guides/geocoder-migration/) guide.
+
+## Overview
+
+`Geocoder` artifact provides a Java wrapper around [Mapbox Geocoding API](https://docs.mapbox.com/api/search/geocoding/) service. 
+
+[MapboxGeocoding](https://github.com/mapbox/mapbox-java/blob/main/services-geocoding/src/main/java/com/mapbox/api/geocoding/v5/MapboxGeocoding.java#L64) is used to request both forward and reverse geocoding information. **Forward geocoding** will take a `String`, such as a street address or point of interest, and transform it into a `Point` object. **Reverse geocoding** does the opposite, taking in a `Point` object and transforming it into an address. The amount of detail provided in the response varies. For example, one response might contain a full address while another response will only contain the city and country.
+
+All of the documentation is available on a [Geocoder documentation page](https://docs.mapbox.com/android/java/guides/geocoder/).