Use correct start page for features component and fix some cross-modu…

…le xrefs

antora/features/antora.yml

@@ -4,6 +4,7 @@
 name: features
 title: Vulkan Feature Descriptions
 version: latest
+start_page: features:index.adoc
 # stem (latexmath) support is provided by the @djencks/asciidoctor-mathjax
 # extension, loaded in the playbook.
 asciidoc:

antora/features/modules/features/pages/index.adoc

@@ -1,14 +1,17 @@
 // Copyright 2022-2024 The Khronos Group Inc.
 // SPDX-License-Identifier: CC-BY-4.0
 
-= Vulkan Roadmap and Feature Descriptions
+= Vulkan Feature Descriptions
 
-This component includes the Vulkan Roadmap, the Vulkan 2022 Profile Roadmap,
-and all published extension feature descriptions.
+This component includes all published extension feature descriptions, as
+well as the original rationale for the xref:proposals/Roadmap.adoc[Vulkan
+Roadmap] process which resulted in the
+xref:spec::appendices/roadmap.adoc[Roadmap 2022 and Roadmap 2024] milestones.
 
-When a Vulkan extension is initially proposed, a feature description is
-written outlining the proposed API, from which specification language is
-written.
-Once the extension is published, the initial "proposal", now
-referred to as a "feature description", is retained to act as
-supplementary documentation on that extension.
+When a Vulkan extension begins development, a "`proposal`" document is
+written outlining the proposed API.
+The proposal is the basis from which specification language is written.
+
+When the extension is published, the proposal - now referred to as a
+"`feature description`" - is retained to act as supplementary documentation
+on that extension.

antora/spec/modules/ROOT/pages/index.adoc

@@ -25,10 +25,10 @@ This build of the site includes the Vulkan {SPECREVISION} API specification
 
 == Navigation
 
-The site is organized in "components" (Antora terminology for
-specifications and other documents), each containing many "pages"
-(Antora terminology for a chapter of a specification, or other distinct
-piece of content for other components).
+The site is organized in "`components`" (Antora terminology for
+specifications and other documents), each containing many "`pages`" (Antora
+terminology for a chapter of a specification, or other distinct piece of
+content for other components).
 
 The left navigation sidebar links to pages in the current component.
 
@@ -37,8 +37,8 @@ The right navigation sidebar links to sections in the current page.
 The bottom-left button switches between components.
 
 The top navigation bar contains a text searchbox.
-If the "In this component" box is checked, search will be
-restricted to the current component.
+If the "`In this component`" box is checked, search will be restricted to
+the current component.
 Otherwise, all components of the site are searched.