Change usage of compile to implementation in docs (gradle). (#332)

React Native bumped the version of the Android Gradle Plugin
to v3 which uses the newer Gradle dependency
configurations `implementation` and `api` which make `compile`
obsolete.

docs/installation-manual.md

@@ -30,10 +30,10 @@ android {
 }
 
 dependencies {
-    compile fileTree(dir: 'libs', include: ['*.jar'])
-    compile "com.android.support:appcompat-v7:23.0.1"
-    compile "com.facebook.react:react-native:+"  // From node_modules
-+   compile project(':react-native-fast-image')
+    implementation fileTree(dir: "libs", include: ["*.jar"])
+    implementation "com.android.support:appcompat-v7:${rootProject.ext.supportLibVersion}"
+    implementation "com.facebook.react:react-native:+"  // From node_modules
++   implementation project(':react-native-fast-image')
 }
 ```