Update tfc-agent changelog (#35)

Author: natalie-todd

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

@@ -16,6 +16,16 @@ 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/).
 
+## 1.6.0 (12/20/2022)
+
+FEATURES:
+
+* Added a new configuration setting for defining the cache directory (#303)
+
+IMPROVEMENTS:
+
+* Increased deadline for "terraform init" process to 10 minutes (#312)
+
 ## 1.5.0 (12/14/2022)
 
 FEATURES:
@@ -28,7 +38,7 @@ BUG FIXES:
 * Fixed hook scripts not executing if the operation errors or exits early (#250)
 * Fixed handling of plugin directory in custom Terraform bundles (#295)
 
-## 1.4.0 (05/10/2022)
+## 1.4.0 (10/05/2022)
 
 IMPROVEMENTS: