chore: Add docs for changing versions of things.

docs/other-android-versions.md

@@ -0,0 +1,25 @@
+# Other Android Versions
+
+If you are not on a clean React Native install you may need to change the versions of some things this library uses.
+
+If you've defined
+_[project-wide-properties](https://developer.android.com/studio/build/gradle-tips.html)_(**recommended**)
+in your root `build.gradle`, this library will detect the presence of the following properties:
+
+```groovy
+buildscript {...}
+allprojects {...}
+
+/**
+ + Project-wide Gradle configuration properties
+ */
+ext {
+    // You can use any of these to change project wide versions:
+    // compileSdkVersion   = 26
+    // targetSdkVersion    = 26
+    // minSdkVersion       = 16
+    // buildToolsVersion   = "26.0.3"
+    // supportLibVersion   = "27.1.1"
+    // glideVersion        = "4.7.1"
+}
+```