Fix #354 Update contributor guide: s/json/yaml/, extension adoc page

build/create-extension-templates/runtime-pom.xml

@@ -31,6 +31,10 @@
     <artifactId>[=artifactId]</artifactId>
     <name>[=namePrefix][=nameBase][=nameSegmentDelimiter]Runtime</name>
 
+    <properties>
+        <firstVersion>[=version?split(".")[0]].[=version?split(".")[1]?number + 1].0</firstVersion>
+    </properties>
+
     <dependencyManagement>
         <dependencies>
             <dependency>

docs/modules/ROOT/pages/contributor-guide.adoc

@@ -95,7 +95,7 @@ TIP: The `nameBase` parameter of the mojo is optional. If you do not specify it
 derive it from `artifactIdBase` by replacing dashes with spaces and capitalizing the first letter of each token. So you
 may consider omitting explicit `nameBase` in some cases.
 
-6. Create `extensions/foo-abc/runtime/src/main/resources/META-INF/quarkus-extension.json`. Consult other existing
+6. Create `extensions/foo-abc/runtime/src/main/resources/META-INF/quarkus-extension.yaml`. Consult other existing
    extensions for the content of the file.
 
 7. Complete the extension by adding dependencies to the runtime module. You probably want to add a dependency on
@@ -108,4 +108,14 @@ may consider omitting explicit `nameBase` in some cases.
 9. In case of problems, consult the https://quarkus.io/guides/extension-authors-guide[Quarkus extension author's guide],
    ask for help in the given GitHub issue or via https://gitter.im/apache/camel-quarkus[Camel Quarkus chat].
 
+10. If the usage of your new extension differs from the usage of the given Camel component, please add an AsciiDoc page
+   under `docs/modules/ROOT/pages/extensions` and document the differences and Quarkus specific configuration options
+   there. For our imaginary Camel component `foo-abc` the complete path of the page would be
+   `docs/modules/ROOT/pages/extensions/foo-abc.adoc`. After completing the page, run `mvn clean install -DskipTests`
+   from the root of the source tree to add your extension to the autogenerated list of extensions.
+
+11. Before sending a pull request, please squash your commits and run
+   `mvn validate -Plicense,sourcecheck -Dcheckstyle.failOnViolation=true` to add license headers to the new files and
+   to make sure that your code is properly formatted.
+
 Good luck!