Update navigation

Author: joshmoore

_data/navigation.yml

@@ -0,0 +1,21 @@
+main:
+  - title: "Tutorial"
+    url: https://zarr.readthedocs.io/en/stable/tutorial.html
+
+sidebar:
+  - title: About
+    children:
+      - title: "Applications"
+        url: '#applications'
+      - title: "Features"
+        url: '#features'
+      - title: "Sponsorship"
+        url: "#sponsorship"
+      - title: "Community Meetings"
+        url: '#community-meetings'
+  - title: Other sites
+    children:
+      - title: "Specification"
+        url: https://zarr-specs.readthedocs.io/en/core-protocol-v3.0-dev/
+      - title: "Implementations"
+        url: https://github.com/zarr-developers/zarr_implementations

index.md

@@ -28,10 +28,14 @@ Zarr data can be stored in any storage system that can be represented as a key-v
 * Read and write arrays concurrently from multiple threads or processes.
 * Organize arrays into hierarchies via annotatable groups.
 
+## Sponsorship
+
 Zarr is a Sponsored Project of NumFOCUS, a US 501(c)(3) public charity.
 
 NumFOCUS Sponsored Projects rely on the generous support of corporate sponsors, institutional partners, and individual donors.
 
+## Videos
+
 <iframe allowfullscreen="allowfullscreen" src="https://www.youtube.com/embed/qyJXBlrdzBs?color=white&theme=light"> </iframe>
 
 ## Community meetings