combine requirements.yaml and Chart.yaml, update CHANGELOG

CHANGELOG.md

+## [0.2.0] - 2021-05-25
+
+* Update Chart to apiVersion 2, move requirements to Chart.yaml
+  NOTE: This means Helm 3 is required to install and maintain the chart
+
 ## [0.1.7] - 2021-05-12
 
 * Add numberic based backup option that uses number-based backup scheme instead

Chart.yaml

 ---
-apiVersion: v1
+apiVersion: v2
 appVersion: "5.4.2"
 description: WordPress with a replicated MariaDB backend
 name: wordpress
 # Please only change the chart version as part of the release procedure: see
 # RELEASING.md
-version: 0.1.7
+version: 0.2.0
 icon: https://make.wordpress.org/design/files/2016/09/WordPress-logotype-wmark.png
+dependencies:
+  - name: mariadb
+    version: 7.3.16
+    repository: "https://charts.bitnami.com/bitnami"
+    tags:
+      - mysql
+    alias: database
+  - name: redis
+    version: 10.5.14
+    repository: "https://charts.bitnami.com/bitnami"
+    condition: redis.enabled
+    tags:
+      - redis

requirements.yaml

-dependencies:
-  - name: mariadb
-    version: 7.3.16
-    repository: "@bitnami"
-    tags:
-      - mysql
-    alias: database
-  - name: redis
-    version: 10.5.14
-    repository: "@bitnami"
-    condition: redis.enabled
-    tags:
-      - redis