Update Readme compile configuration

Configuration 'compile' is obsolete and has been replaced with 'implementation' and 'api'.
It will be removed at the end of 2018. For more information see: http://d.android.com/r/tools/update-dependency-configurations.html

Author: jeremiahAI

README.md

@@ -28,7 +28,7 @@ The minimum supported SDK version is 15
 **Step 2.** Add the dependency
 
     dependencies {
-	     compile 'com.github.Flutterwave:rave-android:1.0.28'
+	     implementation 'com.github.Flutterwave:rave-android:1.0.28'
 	}
 
 **Step 3.** Add the required permission
@@ -169,4 +169,4 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
-```
+```