Add docs folder and Gradle tasks

Author: rainboyan

build.gradle

@@ -26,6 +26,7 @@ apply plugin: "org.graceframework.grace-web"
 apply plugin: "org.graceframework.asset-pipeline"
 apply plugin: "com.github.erdi.webdriver-binaries"
 apply plugin: "org.graceframework.grace-gsp"
+apply from: 'gradle/docs.gradle'
 
 repositories {
     // mavenLocal()

docs/guide/introduction.adoc

@@ -0,0 +1 @@
+Grace Admin is a powerful and flexible, extensible administration framework and management console for Grace.

docs/guide/toc.yml

@@ -0,0 +1,2 @@
+introduction: Introduction
+usage: Usage

docs/guide/usage.adoc

@@ -0,0 +1,24 @@
+== Getting Started
+
+Add `admin` plugin to your `build.gradle`,
+
+[source,groovy]
+----
+apply plugin: "org.graceframework.grace-gsp"
+
+repositories {
+    mavenCentral()
+    maven {
+        url "https://s01.oss.sonatype.org/content/repositories/snapshots/"
+        mavenContent {
+            snapshotsOnly()
+        }
+    }
+}
+
+dependencies {
+    implementation "org.graceframework.plugins:dynamic-modules:1.0.0-RC1"
+    implementation "org.graceframework.plugins:admin:$adminVersion"
+}
+
+----