[ITensors] [DOCUMENTATION] Outdated link refs for SitType

[VinceNeede]

Hi all,
I just spotted what I think are some outdated link refs from the library in the SiteType page.

In particular:

• in SiteType type description

To add new operators to an existing site type, or to create new site types, you can follow the instructions [here](https://itensor.github.io/jl/stable/examples/Physics.html).

to

To add new operators to an existing site type, or to create new site types, you can follow the instructions [here](https://itensor.github.io/ITensors.jl/stable/examples/Physics.htmll).

and

 You can view the source code for the internal SiteType definitions and operators that are defined [here](https://github.com/ITensor/jl/tree/main/src/physics/site_types).

to

 You can view the internal SiteType definitions and operators [here](https://itensor.github.io/ITensors.jl/stable/IncludedSiteTypes.html).

• In op method (https://itensor.github.io/ITensors.jl/stable/SiteType.html#ITensors.SiteTypes.op)

To see all of the operator names defined for the site types included with ITensor, please view the [source code](https://github.com/ITensor/jl/tree/main/src/physics/site_types) for each site type.

to

You can see all of the operator names defined for the site types included with ITensor [here](https://itensor.github.io/ITensors.jl/dev/IncludedSiteTypes.html).

[mtfishman]

Thanks, can you make a PR?

[VinceNeede]

Done just now