feat(zerto): create guide about multisite

[OvhValentin]

<## What type of Pull Request is this?

• New guide(s)
• Index categories update

Description

Refer to SK-2488

Mandatory information

The translations in this Pull Request have been done using:

• [ ] OVHcloud integrated translation LLM
• [ ] Systran
• [ ] Other tool (specify which tool was used)
• [ ] This Pull Request didn't require any translation.

• This Pull Request can be merged as soon as possible.

• This Pull Request content should be replicated for the US OVHcloud documentation : YES/NO

[benchbzh]

Hello @ToutouneOvh, Can you please check the EN proofreading, specifically on the first point (Access Zerto Manager on Managed vSphere) ? The button for adding a Zerto Site is "Add a website" on the OVHcloud Control Panel, should it be "Add a site" (error on the Control Panel)? I also noticed that the network diagram mention "OVH Cloud" and "OVHCloud" : it should be "OVHcloud" > can it be updated? Thanks in advance

[OvhValentin]

ready

[benchbzh]

Thank you for your contribution @OvhValentin!