Add support to run on Kubernetes, add Helm chart

See relevant README.md for more details.

kubernetes/README.md

@@ -0,0 +1,42 @@
+# Invidious Helm chart
+
+Easily deploy Invidious to Kubernetes.
+
+## Installing Helm chart
+
+```sh
+# Build Helm dependencies
+$ helm dep build
+
+# Add PostgreSQL init scripts
+$ kubectl create configmap invidious-postgresql-init \
+  --from-file=../config/sql/channels.sql \
+  --from-file=../config/sql/videos.sql \
+  --from-file=../config/sql/channel_videos.sql \
+  --from-file=../config/sql/users.sql \
+  --from-file=../config/sql/session_ids.sql \
+  --from-file=../config/sql/nonces.sql \
+  --from-file=../config/sql/annotations.sql \
+  --from-file=../config/sql/playlists.sql \
+  --from-file=../config/sql/playlist_videos.sql \
+  --from-file=../config/sql/privacy.sql
+
+# Install Helm app to your Kubernetes cluster
+$ helm install invidious ./
+```
+
+## Upgrading
+
+```sh
+# Upgrading is easy, too!
+$ helm upgrade invidious ./
+```
+
+## Uninstall
+
+```sh
+# Get rid of everything (except database)
+$ helm delete invidious
+
+# To also delete the database, remove all invidious-postgresql PVCs
+```