Fix indentation for all pages

docs/modules/ROOT/pages/README.adoc

@@ -5,7 +5,7 @@ image::https://codecov.io/gh/spring-cloud/spring-cloud-gateway/branch/main/graph
 include::intro.adoc[]
 
 [[features]]
-== Features
+= Features
 
 * Java 17
 * Spring Framework 6
@@ -19,11 +19,11 @@ include::intro.adoc[]
 * Supports Spring Cloud `DiscoveryClient` for configuring Routes
 
 [[building]]
-== Building
+= Building
 
 include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/docs/src/main/asciidoc/building.adoc[]
 
 [[contributing]]
-== Contributing
+= Contributing
 
 include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/docs/src/main/asciidoc/contributing.adoc[]

docs/modules/ROOT/pages/appendix.adoc

@@ -1,7 +1,7 @@
 :numbered!:
 [appendix]
 [[common-application-properties]]
-== Common application properties
+= Common application properties
 
 include::_attributes.adoc[]