Improve Quarkiverse extension codestart initial docs structure

[suryateja-g13]

Problem

When a new Quarkiverse extension is generated with quarkus create extension, the initial docs structure is minimal and inconsistent with how established Quarkiverse extensions organise their documentation:

• The nav only has a single entry: Getting started
• The index.adoc mixes installation instructions with the configuration reference in one page
• There is no dedicated Configuration Reference page

Fix

Introduces a clean two-page structure aligned with established Quarkiverse extensions (e.g. quarkus-web-bundler):

nav.tpl.qute.adoc — adds Configuration Reference alongside Getting started:

* xref:index.adoc[Getting started]
* xref:config-reference.adoc[Configuration Reference]

pages/index.tpl.qute.adoc — focused on installation only:

• Covers both Maven and Gradle (previously Maven only)
• Adds a Usage stub section to guide the developer
• Removes the inline config reference section (now in its own page)

pages/config-reference.tpl.qute.adoc (new file) — dedicated config reference page:

• Includes the auto-generated configuration properties include
• Mirrors the pattern used across Quarkiverse extensions

Before / After

Before — single nav entry, everything crammed into index.adoc:

* Getting started

After — standard two-page structure:

* Getting started
* Configuration Reference

Test plan

• Run quarkus create extension --codestart quarkiverse my-extension and verify the generated docs folder contains both index.adoc and config-reference.adoc
• Verify nav.adoc has both entries
• Verify index.adoc covers Maven + Gradle installation and has a Usage section
• Verify config-reference.adoc exists and includes the config properties include

Fixes #35367

[quarkus-bot]

Status for workflow Quarkus CI

This is the status report for running Quarkus CI on commit cf9c52f.

✅ The latest workflow run for the pull request has completed successfully.

It should be safe to merge provided you have a look at the other checks in the summary.

You can consult the Develocity build scans.

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Flaky tests - Develocity

⚙️ Gradle Tests - JDK 17 Windows

📦 integration-tests/gradle

❌ io.quarkus.gradle.devmode.JandexIncludedBuildTest.main - History

• Condition with Lambda expression in io.quarkus.test.devmode.util.DevModeClient was not fulfilled within 1 minutes 30 seconds. - org.awaitility.core.ConditionTimeoutException

Details

org.awaitility.core.ConditionTimeoutException: Condition with Lambda expression in io.quarkus.test.devmode.util.DevModeClient was not fulfilled within 1 minutes  30 seconds.
	at org.awaitility.core.ConditionAwaiter.await(ConditionAwaiter.java:167)
	at org.awaitility.core.CallableCondition.await(CallableCondition.java:78)
	at org.awaitility.core.CallableCondition.await(CallableCondition.java:26)
	at org.awaitility.core.ConditionFactory.until(ConditionFactory.java:1160)
	at org.awaitility.core.ConditionFactory.until(ConditionFactory.java:1129)
	at io.quarkus.test.devmode.util.DevModeClient.getHttpResponse(DevModeClient.java:164)
	at io.quarkus.gradle.devmode.QuarkusDevGradleTestBase.getHttpResponse(QuarkusDevGradleTestBase.java:170)

[geoand]

Please update the PR description according to https://github.com/quarkusio/quarkus/blob/main/AI_POLICY.md#signal-to-noise-ratio