Add documentation to configure OS X with IPSec

[hakito]

I am new to OPNsense and I could get IPSec working with windows, but not with OS X.

The current documentation

docs/source/manual/how-tos/ipsec-rw.rst

Line 114 in 523630a

:header: "VPN Method", "Win7", "Win10", "Linux", "Mac OS X", "IOS", "Android", "OPNsense config"

refers to the documentation IPsec: Setup OPNsense for IKEv2 EAP-TLS. But is this probably outdated?

docs/source/manual/how-tos/ipsec-rw-srv-eaptls.rst

Line 50 in 523630a

Step 3 - Phase 1 Mobile Clients

Mobile Clients does not have a Phase 1 setup.

[OPNsense-bot]

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[hakito]

Template based version: #623