chore: add 1.28.1 changelog (#860)

Author: Katie Horne

changelog/1.28.1.md

@@ -0,0 +1,25 @@
+---
+title: "1.28.1"
+description: "Released on 02/23/2022"
+---
+
+### Breaking changes ❗
+
+There are no breaking changes in 1.28.1.
+
+### Features ✨
+
+- infra: relaxed the Kubernetes version requirement. Coder requires v1.21 or
+  later and does not support earlier versions. If you opt to use v1.19 or v1.20,
+  you'll see warning messages during the installation process. Coder does not
+  allow the use of v1.18 or earlier.
+
+### Bug fixes 🐛
+
+- infra: fixed issue regarding mTLS not working with Git providers and Docker
+  registries.
+- infra: fixed issue with `coderd` intermittently crashing.
+
+### Security updates 🔐
+
+There are no security updates in 1.28.1.

manifest.json

@@ -535,7 +535,12 @@
       "path": "./changelog/index.md",
       "children": [
         {
-          "path": "./changelog/1.28.0.md"
+          "path": "./changelog/1.28.0.md",
+          "children": [
+            {
+              "path": "./changelog/1.28.1.md"
+            }
+          ]
         },
         {
           "path": "./changelog/1.27.0.md",