Add integration instructions and migration guide (#3)

Author: mickael-menu

README.md

@@ -1,2 +1,98 @@
 # Readium Kotlin Toolkit
 
+[Readium Mobile](https://github.com/readium/mobile) is a toolkit for ebooks, audiobooks and comics written in Swift & Kotlin.
+
+This toolkit is a modular project, which follows the [Readium Architecture](https://github.com/readium/architecture). The different modules are found under [`readium/`](readium).
+
+* [`shared`](readium/shared) – Shared `Publication` models and utilities
+* [`streamer`](readium/streamer) – Publication parsers and local HTTP server
+* [`navigator`](readium/navigator) – Plain `Fragment` and `Activity` classes rendering publications
+* [`opds`](readium/opds) – Parsers for OPDS catalog feeds
+* [`lcp`](readium/lcp) – Service and models for [Readium LCP](https://www.edrlab.org/readium-lcp/)
+
+A [Test App](test-app) demonstrates how to integrate the Readium Kotlin toolkit in your own reading app
+
+## Using Readium
+
+Readium modules are distributed through [JitPack](https://jitpack.io/#readium/kotlin-toolkit). It's also possible to clone the repository (or a fork) and depend on the modules locally.
+
+### From the JitPack Maven repository
+
+Make sure that you have the `$readium_version` property set in your root `build.gradle` and add the JitPack repository.
+
+```gradle
+buildscript {
+    ext.readium_version = '2.1.0'
+}
+
+allprojects {
+    repositories {
+        maven { url 'https://jitpack.io' }
+    }
+}
+```
+
+Then, add the dependencies to the Readium modules you need in your app's `build.gradle`.
+
+```gradle
+dependencies {
+    implementation "com.github.readium.kotlin-toolkit:readium-shared:$readium_version"
+    implementation "com.github.readium.kotlin-toolkit:readium-streamer:$readium_version"
+    implementation "com.github.readium.kotlin-toolkit:readium-navigator:$readium_version"
+    implementation "com.github.readium.kotlin-toolkit:readium-opds:$readium_version"
+    implementation "com.github.readium.kotlin-toolkit:readium-lcp:$readium_version"
+}
+```
+
+### From a local Git clone
+
+You may prefer to use a local Git clone if you want to contribute to Readium, or if you are using your own fork.
+
+First, add the repository as a Git submodule of your app repository, then checkout the desired branch or tag:
+
+```sh
+git submodule add https://github.com/readium/kotlin-toolkit.git
+```
+
+Next, declare the Kotlin version used in your root `build.gradle`.
+
+```gradle
+buildscript {
+    ext.kotlin_version = '1.5.31'
+}
+```
+
+Then, add the following to your project's `settings.gradle` file, altering the paths if needed. Keep only the modules you want to use.
+
+```gradle
+include ':readium:shared'
+project(':readium:shared').projectDir = file('kotlin-toolkit/readium/shared')
+
+include ':readium:streamer'
+project(':readium:streamer').projectDir = file('kotlin-toolkit/readium/streamer')
+
+include ':readium:navigator'
+project(':readium:navigator').projectDir = file('kotlin-toolkit/readium/navigator')
+
+include ':readium:opds'
+project(':readium:opds').projectDir = file('kotlin-toolkit/readium/opds')
+
+include ':readium:lcp'
+project(':readium:lcp').projectDir = file('kotlin-toolkit/readium/lcp')
+```
+
+You should now see the Readium modules appear as part of your project. You can depend on them as you would on any other local module:
+
+```
+dependencies {
+    implementation project(':readium:shared')
+    implementation project(':readium:streamer')
+    implementation project(':readium:navigator')
+    implementation project(':readium:opds')
+    implementation project(':readium:lcp')
+}
+```
+
+### Building with Readium LCP
+
+Using the toolkit with Readium LCP requires additional dependencies, including the binary `liblcp` provided by EDRLab. [Contact EDRLab](mailto:contact@edrlab.org) to request your private `liblcp` and the setup instructions.