Update docs banner for Icechunk 2.0 (#2052)

## Summary
- Update the homepage announcement banner from Icechunk 1.0 to 2.0
- Update banner text to highlight key 2.0 features: JavaScript support,
stronger consistency, and higher performance
- Update blog post link to point to the 2.0 announcement
- Fix minor HTML typo (`</a.` → `</a>.`)

closes #2053

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: TomNicholas

README.md

@@ -10,7 +10,7 @@
 
 ---
 > [!TIP]
-> **Icechunk 1.0 is released!** Better API, more performance and stability
+> **Icechunk 2.0 is released!** Better consistency, performance, and reliability for tensor storage
 ---
 
 Icechunk is an open-source (Apache 2.0), transactional storage engine for tensor / ND-array data designed for use on cloud object storage.

icechunk-python/docs/overrides/home.html

@@ -2,7 +2,7 @@
 
 <!-- Announcement bar -->
 {% block announce %}
-  <div class="banner">Announcing Icechunk 1.0: Ready for production workloads. <a href="https://earthmover.io/blog/icechunk-1-0-production-grade-cloud-native-array-storage-is-here" target="_blank">Read more</a.</div>
+  <div class="banner">Announcing Icechunk 2.0: Better consistency, performance, and reliability for tensor storage. <a href="https://earthmover.io/blog/announcing-icechunk-2-better-consistency-performance-and-reliability-for-tensor-storage" target="_blank">Read more</a>.</div>
 {% endblock %}