Update agent version to v2.8.1. (#511)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

charts/netdata/Chart.yaml

@@ -15,4 +15,4 @@ maintainers:
   - name: Netdata Cloud SRE team
     email: [email protected]
 icon: https://netdata.github.io/helmchart/logo.png
-appVersion: v2.8.0
+appVersion: v2.8.1

charts/netdata/README.md

@@ -4,7 +4,7 @@
 
 <img src="https://img.shields.io/badge/Version-3.7.152-informational" alt="Version: 3.7.152"></img>
 
-<img loading="lazy" src="https://img.shields.io/badge/AppVersion-v2.8.0-informational" alt="AppVersion: v2.8.0" class="img_node_modules-@docusaurus-theme-classic-lib-theme-MDXComponents-Img-styles-module"></img>
+<img loading="lazy" src="https://img.shields.io/badge/AppVersion-v2.8.1-informational" alt="AppVersion: v2.8.1" class="img_node_modules-@docusaurus-theme-classic-lib-theme-MDXComponents-Img-styles-module"></img>
 
 _Based on the work of varyumin (https://github.com/varyumin/netdata)_.