Add "following organizations" section to "Be social" (#30143)

data/reusables/organizations/about-following-organizations.md

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+When you follow organizations on {% data variables.product.product_name %}, you'll see their {% ifversion fpt or ghec %}public{% endif %} activity on your personal dashboard. This activity includes new discussions, sponsorships, and repositories.

data/reusables/organizations/follow-organizations-beta.md

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+{% note %}
+
+**Note:** The ability to follow organizations is currently in public beta and subject to change.
+
+{% endnote %}