Update add-storage-space.md

[msbemba]

trafficstars

Made changes to the way we purchase add-s as it is in purchase services page now

Fixes https://github.com/MicrosoftDocs/microsoft-365-docs/issues/12688

[msbemba]

@JohanFreelancer9 Please copy review

[learn-build-service-prod[bot]]

Learn Build status updates of commit 1183336:

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microsoft-365/commerce/add-storage-space.md	:white_check_mark:Succeeded

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[yogkumgit]

@cmcatee-MSFT Please merge this PR. Thanks

[yogkumgit]

@cmcatee-MSFT Gentle reminder. Thanks