Add Contributing file (foundation-model-stack#58)

* Add Contributing file

Signed-off-by: James Busche <jbusche@us.ibm.com>

* add issue templates

Signed-off-by: James Busche <jbusche@us.ibm.com>

* Adding Alex to CODEOWNERS

Signed-off-by: James Busche <jbusche@us.ibm.com>

* Add ADR and squash info

Signed-off-by: James Busche <jbusche@us.ibm.com>

* Update CONTRIBUTING.md

Signed-off-by: Sukriti Sharma <Ssukriti@users.noreply.github.com>

* NIT: Update CONTRIBUTING.md

Signed-off-by: Sukriti Sharma <Ssukriti@users.noreply.github.com>

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Signed-off-by: James Busche <jbusche@us.ibm.com>
Signed-off-by: Sukriti Sharma <Ssukriti@users.noreply.github.com>
Co-authored-by: Sukriti Sharma <Ssukriti@users.noreply.github.com>