Add playbook to Spring Session

spring-session-docs/spring-session-docs.gradle

@@ -1,3 +1,7 @@
+plugins {
+    id "io.github.rwinch.antora" version "0.0.2"
+}
+
 apply plugin: 'io.spring.convention.docs'
 apply plugin: 'io.spring.convention.spring-test'
 
@@ -23,6 +27,19 @@ dependencies {
 	testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine'
 }
 
+antora {
+    antoraVersion = "3.0.0-alpha.8"
+    arguments = ["--fetch"]
+}
+
+tasks.antora {
+    environment = [
+            "ALGOLIA_API_KEY" : "82c7ead946afbac3cf98c32446154691",
+            "ALGOLIA_APP_ID" : "244V8V9FGG",
+            "ALGOLIA_INDEX_NAME" : "session-docs"
+    ]
+}
+
 sourceSets {
     test {
         java {