improves the documentation

README.md

@@ -107,6 +107,9 @@ Three formatters are included out of the box:
 * `MySQL` returns a MySQL DataSource.
 * `PostgreSQL` returns a PostgreSQL DataSource.
 * `Redis` returns a Redis JedisPool.
+* `Solr` returns a HttpSolrClient instance.
+* `Memcached` returns a MemcachedClient instance.
+* `Elasticsearch` returns a RestHighLevelClient instance.
 * `RedisSpring` returns JedisConnectionFactory to Spring Data.
 
 ### Reading Platform.sh variables
@@ -134,4 +137,4 @@ The `route()` method takes a single string for the route ID ("main" in this case
 
 To access all routes, or to search for a route that has no ID, the `routes()` method returns an dictionary of routes keyed by their URL.  That mirrors the structure of the `PLATFORM_ROUTES` environment variable.
 
-If called in the build phase an exception is thrown.
+If called in the build phase an exception is thrown.