Add CITATION.cff for Standardized Ibex Citations

[FelixUhle]

Hi Ibex-team,

I’d like to propose adding a CITATION.cff file to the Ibex repository. This would help researchers and users cite Ibex consistently in academic (and professional) work.
I’ve generated a draft using cffinit as a starting point:

# This CITATION.cff file was generated with cffinit.
# Visit https://bit.ly/cffinit to generate yours today!

cff-version: 1.2.0
title: Ibex
message: >-
  If you use this software, please cite it using the
  metadata from this file.
type: software
authors:
  - name: lowRISC CIC
    address: 7 Hills Road
    city: Cambridge
    post-code: CB2 1GE
    country: GB
    website: 'https://lowrisc.org/'
abstract: >-
  Ibex is a production-quality open source 32-bit RISC-V CPU
  core written in SystemVerilog. The CPU core is heavily
  parametrizable and well suited for embedded control
  applications. Ibex is being extensively verified and has
  seen multiple tape-outs. Ibex supports the Integer (I) or
  Embedded (E), Integer Multiplication and Division (M),
  Compressed (C), and B (Bit Manipulation) extensions.

Open Questions:

1. Authorship: Should lowRISC CIC be the sole author, or would it be more appropriate to include the PULP Platform as a co-author (or primary author)?

2. Additional Metadata: Would you like to add a DOI, ORCID, version, or specific contributors (e.g., key maintainers) to the file?

3. Preferred Citation Format: Do you have existing guidelines for how Ibex should be cited (e.g., in papers or documentation, which I have missed)?

I’m happy to refine this further or submit a PR. Thanks for considering this!

Best,
Felix Uhle

[Razer6]

1. Authorship: Should lowRISC CIC be the sole author, or would it be more appropriate to include the PULP Platform as a co-author (or primary author)?

Also, LowRISC CIC is, I think, not the right author as the project has contributions from many different people apart from this company.