[doc] Improve offline Jazzy documentation layout

- Group classes in sidebar sections.
- Use the offline mode guide as an overview for the section (I had to rename the file and remove the main heading).

[ci skip]

Author: Clément Le Provost

doc/offline-mode.md renamed to doc/Offline mode.md

@@ -1,7 +1,5 @@
 
 
-# Offline mode
-
 ## Overview
 
 The API client can be enhanced with offline capabilities. This optional **offline mode** allows you to mirror online indices on local storage, and transparently switch to the local mirror in case of unavailability of the online index, thus providing uninterrupted user experience. You can also explicitly query the mirror if you want.
@@ -210,4 +208,3 @@ If you have a crash in the offline core, please send us a support request. Make
 ## Other resources
 
 The offline client bears extensive documentation comments. Please refer to them for more details.
-

offline.jazzy.yaml

@@ -5,11 +5,33 @@ xcodebuild_arguments:
     - AlgoliaSearch.xcworkspace
     - -scheme
     - AlgoliaSearch-Offline-iOS
-documentation:
-    - doc/offline-mode.md
 output: build/doc
 # Avoid putting the DocSet within the HTML docs.
 # WARNING: The path is relative to the output directory.
 docset_path: ../docset
 hide_documentation_coverage: true
 skip_undocumented: true
+
+custom_categories:
+    - name: API Client
+      children:
+        - Client
+        - Index
+        - Query
+        - BrowseIterator
+
+    - name: Auxiliary types
+      children:
+        - GeoRect
+        - IndexQuery
+        - LatLng
+        - LibraryVersion
+
+    - name: Offline mode
+      children:
+        - OfflineClient
+        - MirroredIndex
+        - DataSelectionQuery
+
+abstract:
+    - doc/Offline mode.md