update hvac Python module example to avoid running into permission issues

[mababio]

Decided to use Hashicorp Vault Secret manager and spent days trying to read secrets using the hvac python module.

Faced permission issues even though I followed example code:

raise exceptions.VaultError.from_status( hvac.exceptions.Forbidden: 1 error occurred: * permission denied

I created a dev vault cluster managed by Hashicorp. Not sure if the issue exists if Vault cluster was hosted else where.

After specifying namespace in the Client method, I was able to read the secret

Description

Added namespace in the Client method and added a short comment. Also added another minor comment

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

create a Hasicorp Vault managed cluster and attempt to use the example without mentioning namespace in the Client method and see if it fails. if it does, try to mention namespace and see if it passes

[hashicorp-cla]

All committers have signed the CLA.

[mababio]

@digivava when you get a chance

[dhuckins]

think admin namespace is a special child, think we can comment this out?

Suggested change

	namespace='admin', # If namespace is configured, make sure to set here
	# namespace='admin', # If namespace is configured, make sure to set here

[digivava]

These examples are used on our Developer Quickstart page, which currently is written to test against a locally running dev Vault server. So the easiest way to not rewrite the whole quickstart doc right now would probably just be to include a comment like this:

# On HCP Vault clusters, all secrets live within a top-level 'admin' namespace. This can be specified with namespace='admin' when initializing the client.
client = hvac.Client(
    url='http://127.0.0.1:8200',
    ...

We will probably want to add that comment to the rest of the language examples as well, not just Python.

[mababio]

@digivava lgtm