feat!: Remove support for old version of Node.js (#210)

Add support policy, and remove support for 8 and 10.
These version may still work, but they are not supported or tested in our CI

BREAKING CHANGE: Removing Node.Js 8 and 10 from CI

.github/workflows/ci-unit-tests.yaml

@@ -13,9 +13,9 @@ jobs:
           - windows-latest
           - macos-latest
         node:
-          - 10
           - 12
           - 14
+          - 16
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v1

SUPPORT_POLICY.rst

@@ -0,0 +1,38 @@
+Overview
+========
+This page describes the support policy for the AWS Crypto Helpers.
+We regularly provide the AWS Crypto Helpers with updates
+that may contain support for new or updated APIs, new features, enhancements, bug fixes, security patches, or documentation updates.
+Updates may also address changes with dependencies, language runtimes, and operating systems.
+
+We recommend users to stay up-to-date with AWS Crypto Helpers releases
+to keep up with the latest features, security updates, and underlying dependencies.
+Continued use of an unsupported SDK version is not recommended and is done at the user’s discretion.
+
+
+Major Version Lifecycle
+========================
+The AWS Crypto Helpers follows the same major version lifecycle as the AWS SDK.
+For details on this lifecycle, see  `AWS SDKs and Tools Maintenance Policy`_.
+
+Version Support Matrix
+======================
+This table describes the current support status of each major version of the AWS Crypto Helpers.
+It also shows the next status each major version will transition to, and the date at which that transition will happen.
+
+.. list-table::
+    :widths: 30 50 50 50
+    :header-rows: 1
+
+    * - Major version
+      - Current status
+      - Next status
+      - Next status date
+    * - 1.x
+      - Maintenance
+      - End of Support
+      - 2022-04-15
+    * - 2.x
+      - General Availability
+
+.. _AWS SDKs and Tools Maintenance Policy: https://docs.aws.amazon.com/sdkref/latest/guide/maint-policy.html#version-life-cycle