ee_reference.rst: refert to Builder's definition docs instead of duplicating its content

[Andersson007]

SUMMARY

https://docs.ansible.com/automation-controller/latest/html/userguide/ee_reference.html#execution-environment-definition duplicates content from Builder's docs, so we'll be just referring to it to avoid divergence and confusion.

ISSUE TYPE

• Bug, Docs Fix or other nominal change

COMPONENT NAME

• Docs

AWX VERSION

latest

[Andersson007]

ready_for_review

[Andersson007]

@jbericat @Zokormazo @gundalow thanks for reviewing and merging!

[tvo318]

@Andersson007 @gundalow - So the reason why we put the builder v3 content in the automation controller docs was because I was told that we don't want to reference upstream docs for downstream readers. If that is ok, then I'll know next time where duplicate content exist to not duplicate the content.

[Andersson007]

@tvo318 thanks for the context, if you recall the rationale for that, it'd be great, maybe it's reasonable, i don't know, but if we use builder to build the images i think we should refer to their docs as it's the most relevant and updated, etc.