vpn mentioned in readme not accurate

[vburckhardt]

the module does not create vpn gw, however readme states:

VPN gateways: Create VPN gateways on your subnets by using the vpn_gateways variable. For more information about VPN gateways on VPC, see [About site-to-site VPN gateways](https://cloud.ibm.com/docs/vpc?topic=vpc-using-vpn) in the IBM Cloud docs.
VPN gateway connections: Add connections to a VPN gateway.

[ocofaigh]

We also need to update the diagram to remove VPE gw from it

[imprateeksh]

Adding the changes in the PR #927

[imprateeksh]

Creating a new .svg diagram as currently the .png image is present. Will include the same in .docs directory.

[imprateeksh]

Adding the changes in the PR #927

This PR was merged already, I will be raising another PR.

[imprateeksh]

Raised PR - #938

[imprateeksh]

Changes have been made but holding this because of VPC DA changes, mentioned here

[imprateeksh]

@vburckhardt @rajatagarwal-ibm
We have now VPN Gateway as part of this module.
Can we close this issue ?