Build antora docs (main branch) (asciidoctor#722)

* Moved docs to an Antora structure under '/docs'
  * Created antora.yaml
  * Added nav.adoc respecting current structure.
  * Created modules 'ROOT' and 'apendices'
  * Moved source files to respective modules
  * Updated section level (reduced in 1)
  * Created soft link to include content from project sources
 
* Cleaned README.adoc
  * Removed un-used attributes
  * Updated content
* Removed now unnecessary elements:
  * Gradle docs modules
  * 'push-documentation' GH Action
* Fixes:
  * Fixed invalid references (I am not upgrading all references from [legacy to modern](https://docs.asciidoctor.org/asciidoc/latest/sections/custom-ids/) in this PR)
  * Several typos & formatting
Outside of the PR I renamed development-v3.x branch to maintenance-3.x, to align with the documentation done prior to my changes.

.github/workflows/build.yaml

@@ -1,5 +1,14 @@
 name: Build
-on: [push, pull_request]
+on:
+  push:
+    paths-ignore:
+      - '*.adoc'
+      - docs/**
+  pull_request:
+    paths-ignore:
+      - '*.adoc'
+      - docs/**
+
 jobs:
   check:
     runs-on: ubuntu-latest

README.adoc

@@ -1,24 +1,9 @@
 = Asciidoctor Gradle Plugin
 Andres Almiray <https://github.com/aalmiray[@aalmiray]>
-:version: 4.0.0
-:version-published: 4.0.0-alpha.1
-:asciidoc-url: http://asciidoc.org
-:asciidoctor-url: http://asciidoctor.org
-:issues: https://github.com/asciidoctor/asciidoctor-gradle-plugin/issues
+:asciidoc-url: https://asciidoc.org
+:asciidoctor-url: https://asciidoctor.org
 :gradle-url: http://gradle.org/
-:asciidoctor-maven-plugin: https://github.com/asciidoctor/asciidoctor-maven-plugin
-:kotlindsl: https://github.com/gradle/kotlin-dsl[Gradle Kotlin DSL]
-:lightguard: https://github.com/LightGuard
-:asciidoctorj: https://github.com/asciidoctor/asciidoctorj
-:asciidoctorj-name: AsciidoctorJ
-:asciidoctorjs-name: Asciidoctor.js
-:asciidoctorj-epub-name: Asciidoctorj-EPUB
-:asciidoctorj-pdf-name: Asciidoctorj-PDF
-:lordofthejars: https://github.com/lordofthejars
-:asciidoctor-docs: http://asciidoctor.org/docs/
 :asciidoctor-development-docs: https://asciidoctor.github.io/asciidoctor-gradle-plugin/
-:plugin-name: Asciidoctor Gradle plugin
-:project-name: asciidoctor-gradle-plugin
 :project-full-path: asciidoctor/asciidoctor-gradle-plugin
 :github-branch: master
 :linkattrs:
@@ -36,9 +21,9 @@ ifdef::env-github[]
 endif::[]
 
 ifdef::status[]
-image:https://github.com/asciidoctor/asciidoctor-gradle-plugin/workflows/Build/badge.svg[GitHub Actions Status, link=https://github.com/asciidoctor/asciidoctor-gradle-plugin/actions]
-image:http://img.shields.io/coveralls/{project-full-path}/{github-branch}.svg[Coverage Status, link=https://coveralls.io/r/{project-full-path}]
-image:http://img.shields.io/badge/license-ASF2-blue.svg[Apache License 2, link=http://www.apache.org/licenses/LICENSE-2.0.txt]
+image:https://github.com/asciidoctor/asciidoctor-gradle-plugin/workflows/Build/badge.svg[GitHub Actions Status,link=https://github.com/asciidoctor/asciidoctor-gradle-plugin/actions]
+image:http://img.shields.io/coveralls/{project-full-path}/{github-branch}.svg[Coverage Status,link=https://coveralls.io/r/{project-full-path}]
+image:http://img.shields.io/badge/license-ASF2-blue.svg[Apache License 2,link=http://www.apache.org/licenses/LICENSE-2.0.txt]
 image:https://gitlab.com/asciidoctor/asciidoctor-gradle-plugin/badges/master/pipeline.svg[link="https://gitlab.com/asciidoctor/asciidoctor-gradle-plugin/commits/master",title="pipeline status"]
 endif::[]
 
@@ -54,4 +39,3 @@ PRs are preferably taking against this branch.
 The 3.x series of the plugin is now in maintenance only mode.
 PRs for that should be raised against the link:https://github.com/asciidoctor/asciidoctor-gradle-plugin/tree/maintenance-3.x[maintenance-3.x]branches.
 endif::[]
-

base/src/main/groovy/org/asciidoctor/gradle/base/AbstractImplementationEngineExtension.groovy

@@ -52,7 +52,8 @@ class AbstractImplementationEngineExtension
        tag::extension-property[]
         attributes:: Asciidoctor attributes.
           Use `attributes` to append and `setAttributes` to replace any current attributes with a new set.
-          Attribute values are lazy-evaluated to strings. See <<attributes>> for more detail.
+          Attribute values are lazy-evaluated to strings.
+          See <<options-and-attributes,Setting Attributes>> for more detail.
        end::extension-property[]
        ------------------------- */
 

docs/antora.yml

@@ -0,0 +1,34 @@
+name: gradle-plugin
+title: Gradle Plugin Suite
+version: '4.0'
+asciidoc:
+  attributes:
+    release-version: 4.0.2
+    project-full-path: asciidoctor/asciidoctor-gradle-plugin
+    project-name: asciidoctor-gradle-plugin
+    project-repo-url: https://github.com/asciidoctor/asciidoctor-gradle-plugin
+    plugin-name: Asciidoctor Gradle plugin
+    asciidoc-url: https://asciidoc.org
+    asciidoc-docs: https://docs.asciidoctor.org/asciidoc/latest
+    asciidoctor-docs: https://docs.asciidoctor.org/asciidoctor/latest
+    asciidoctor-maven-plugin-name: Asciidoctor Maven Plugin
+    asciidoctor-maven-plugin-url: https://github.com/asciidoctor/asciidoctor-maven-plugin
+    asciidoctor-url: https://asciidoctor.org
+    asciidoctorj-epub-name: Asciidoctorj EPUB3
+    asciidoctorj-epub-url: https://github.com/asciidoctor/asciidoctorj-epub3
+    asciidoctorj-name: AsciidoctorJ
+    asciidoctorj-pdf-name: Asciidoctorj PDF
+    asciidoctorj-pdf-url: https://github.com/asciidoctor/asciidoctorj-pdf
+    asciidoctorj-url: https://github.com/asciidoctor/asciidoctorj
+    asciidoctorjs-name: Asciidoctor.js
+    asciidoctorjs-url: https://github.com/asciidoctor/asciidoctor.js
+    gradle-url: https://gradle.org/
+    issues-asciidoctorj: https://github.com/asciidoctor/asciidoctorj/issues/
+    issues-jruby: https://github.com/asciidoctor/asciidoctorj/issues/
+    jruby-name: JRuby
+    kotlindsl: https://github.com/gradle/kotlin-dsl[Gradle Kotlin DSL]
+    lightguard: https://github.com/LightGuard[Jason Porter]
+    lordofthejars: https://github.com/lordofthejars[Alex Soto]
+nav:
+  - modules/ROOT/nav.adoc
+  - modules/appendices/nav.adoc