fix: replace Group Administrator with Org Administrator

[dawoudt-okta]

Group creation and deletion requires org administrator. Group administrator only allows adding and removing members

[acrolinxdevdocs-okta]

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Article	Total score Required:80	Word and phrases (Brand, terms) Preferred: 80	Correctness (Spelling, grammar) Preferred: 80	Clarity (Readability) Preferred: 80	Inclusive language (+ accesibility) Preferred: 80
✅ packages/@okta/vuepress-site/docs/guides/terraform-enable-org-access/main/index.md	84	94	59	83	100

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[brianduffield-okta]

Pinged @mauricesharp-okta for a SME review/approve. Thanks for opening the PR, @dawoudt-okta

[mauricesharp-okta]

This information is already incorporated in the updated version of the article written by an external contractor. Please close this PR.