website: update static lint configs

- Added support for TypeScript to eslint
- Updated stylelint config to match pkgsite
- Removed redundant prettier config

Change-Id: Ibbc6ff016011be83fc5f2bea7cdd0c4fce7c8929
Reviewed-on: https://go-review.googlesource.com/c/website/+/373719
Trust: Jamal Carvalho <jamalcarvalho@google.com>
Run-TryBot: Jamal Carvalho <jamal@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Alex Rakoczy <alex@golang.org>
diff --git a/.eslintrc.yaml b/.eslintrc.yaml
new file mode 100644
index 0000000..5a9c47b
--- /dev/null
+++ b/.eslintrc.yaml
@@ -0,0 +1,20 @@
+root: true
+extends: google
+parserOptions:
+  ecmaVersion: 6
+rules:
+  require-jsdoc: 'off'
+  indent: 'off'
+  arrow-parens: 'off'
+overrides:
+  - files:
+    - "*.ts"
+    parser: '@typescript-eslint/parser'
+    env:
+      browser: true
+    plugins:
+      - '@typescript-eslint'
+    extends:
+      - eslint:recommended
+      - plugin:@typescript-eslint/recommended
+      - plugin:prettier/recommended