Clarify use of Ibex "simple-system"

[MikeOpenHWGroup]

Task Description

As reported in #263, this repository has an examples/simple_system directory. Typically CORE-V core repositories do not include such examples as our members tend to have their own in-house, proprietary systems. We need to make a conscious decision about what to do about all of the "examples" in the directory of the same name.

Description of Done

One of the following:

1. Delete cve2/examples altogether and remove any references to it in all READMEs and the User Manual.
2. Update the examples to work in the CVE2 context.

Associated PRs

No response

[MarioOpenHWGroup]

Flo, Davide, Duncan and Mario agreed to option 1. @MikeOpenHWGroup do you agree?

[MikeOpenHWGroup]

Yes, I do agree. I'll take this one. Expect a PR in the coming days...

[MikeOpenHWGroup]

Created pull-request #272 to implement option 1, above.

[MikeOpenHWGroup]

As #272 is merged in, this task is Complete.