Updates for tfc-agent release 1.21.2 (#142)

Author: ryanuber

website/docs/cloud-docs/agents/changelog.mdx

@@ -18,6 +18,13 @@ within each release are categorized into one or more of the following labels:
 Each version below corresponds to a release artifact available for download on
 the official [releases website](https://releases.hashicorp.com/tfc-agent/).
 
+## 1.21.2 (04/03/2025)
+
+BUG FIXES:
+
+* Silenced profiler errors on systems where i/o data is unavailable (#973)
+* Fixed spurious 404 errors seen as workloads are completed (#667)
+
 ## 1.21.1 (04/01/2025)
 
 SECURITY: