Update README.md (#17)

README.md

@@ -1 +1,32 @@
 # maven-central
+
+Project isolation compatible publishing plugin, supporting [the new Central Portal Publishing API](https://central.sonatype.org/publish/publish-portal-api/) only.
+
+## Install
+
+This package/Gradle plugin is uploaded to MavenCentral and GitHub packages.
+
+```kotlin
+// settings.gradle (.kts)
+pluginManagement {
+  repositories {
+    mavenCentral()
+  }
+}
+```
+
+## Usage
+
+Install the plugin in each project.
+
+```kotlin
+// build.gradle (.kts)
+plugins {
+  id("io.github.hfhbd.mavencentral") version "LATEST"
+}
+```
+
+You need to setup and configure the publications using the core `maven-publish` and `signing` plugins.
+
+To publish the publications, call `./gradlew publishToMavenCentral -PmavenCentralUsername=MYUSERNAME -PmavenCentralPassword=MYSECRETPASSWORD`.
+Publishing uses the default automatic behavior.