Update README.md and NOTES.txt

- README: Added setting default storageclass to install section before  install command to help prevent issues at first install and subsequent upgrades.
- NOTES: Changed root password update command to use local chart instead of non-existent repo. Once our official `graylog/graylog` repo is created we should change it back though.

Signed-off-by: William Trelawny <22324745+williamtrelawny@users.noreply.github.com>

Author: williamtrelawny

README.md

@@ -33,6 +33,17 @@ git clone git@github.com:Graylog2/graylog-helm.git
 cd graylog-helm
 ```
 
+### Set default StorageClass
+***If your cluster already has a default `storageclass` you can skip this step.***
+
+If not, you're unsure, or you don't want to affect cluster-wide settings, set the default `storageclass` for this Chart at runtime by passing `--set global.defaultStorageClass="my-sc"` to your `helm install` command. Or by adding the following lines to `values-custom.yaml`:
+```
+global:
+  defaultStorageClass: "my-sc"
+```
+
+Just be sure to pass `-f values-custom.yaml` to your `helm install` command below!
+
 ### Set Root Graylog Password
 ```sh
 read -sp "Enter your new password and press return: " pass

graylog/templates/NOTES.txt

@@ -48,7 +48,7 @@ Welcome to Graylog!
 
 · WARNING: You are still using the default password {{ include "graylog.rootPassword" . | quote }}. This MUST be changed IMMEDIATELY using the following command:
 
-    read -sp "Enter your new password and press return: " i && helm upgrade {{ .Release.Name }} graylog/graylog --namespace {{ .Release.Namespace }} --reuse-values --set "graylog.config.rootPassword=$i"
+    read -sp "Enter your new password and press return: " i && helm upgrade {{ .Release.Name }} ./graylog --namespace {{ .Release.Namespace }} --reuse-values --set "graylog.config.rootPassword=$i"
 {{- end }}
 
 · Use the following command to print this status page again: