Fix link to samples

See gh-208

Author: rstoyanchev

spring-graphql-docs/antora.yml

@@ -29,4 +29,5 @@ asciidoc:
     javadoc: https://docs.spring.io/spring-graphql/docs/{spring-graphql-version}/api
     # version attributes from main build.gradle
     spring-framework-ref-docs: https://docs.spring.io/spring-framework/reference
-    spring-boot-ref-docs: https://docs.spring.io/spring-boot/docs/{spring-boot-version}/reference/html
+    spring-boot-ref-docs: https://docs.spring.io/spring-boot/docs/{spring-boot-version}/reference/html
+    examples-repo: https://github.com/spring-projects/spring-graphql-examples

spring-graphql-docs/modules/ROOT/pages/samples.adoc

@@ -1,4 +1,4 @@
 [[samples]]
 = Samples
 
-Please, see the [spring-graphql-examples](https://github.com/spring-projects/spring-graphql-examples) repository.
+Please, see the {examples-repo}[spring-graphql-examples] repository.