Release patch for 0.26.8 (#6579)

# Description

Releasing patch 0.26.8.
  * Add 0.26.8 release notes
  * Update `version.yaml`

## Type of change

- This pull request fixes a bug in Radius and has an approved issue
(issue link required).


## Auto-generated summary

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### Summary
🐛✨⬆️

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Updated the supported version of the `0.26` channel to `v0.26.8` in
`versions.yaml`. This aligns the channel with the latest release of the
radius project.

> _`0.26` channel_
> _Updated to the latest patch_
> _Autumn bugs are fixed_

### Walkthrough
* Update the supported version of the 0.26 channel to v0.26.8
([link](https://github.com/radius-project/radius/pull/6579/files?diff=unified&w=0#diff-1c4cd801df522f4a92edbfb0fea95364ed074a391ea47c284ddc078f512f7b6aL3-R3))

---------

Signed-off-by: Shalabh Mohan Shrivastava <[email protected]>

docs/release-notes/v0.26.8.md

@@ -0,0 +1,7 @@
+## Radius v0.26.8
+
+This release addresses an issue with the Radius Dev Recipes for Dapr resources. Check out the [changelog](#changelog) for more details of what was addressed in this patch.
+
+## Changelog
+
+- Fix for Dapr Statestores and Secretstores dev Recipes URL casing by @shalabhms in https://github.com/radius-project/radius/pull/6578

versions.yaml

@@ -1,6 +1,6 @@
 supported:
   - channel: '0.26'
-    version: 'v0.26.7'
+    version: 'v0.26.8'
 deprecated:
   - channel: '0.25'
     version: 'v0.25.0'