[Content Gap] Add cloud data governance and FedRAMP resource

## What needs to change
The site has no resources connecting data governance practices to cloud migration or FedRAMP. As agencies have moved data workloads to cloud environments this has become a core practical concern for federal data practitioners, but a visitor to resources.data.gov would find nothing to help them navigate it.

## What to research and create
This issue requires research before any files are created. Start by identifying what authoritative resources already exist:

**FedRAMP:**
- Visit https://www.fedramp.gov/resources/ and identify any guidance documents relevant to data governance in cloud environments
- Look for FedRAMP documents addressing data residency, data portability, or data classification in cloud systems

**NIST:**
- Review NIST SP 800-210 (General Access Control Guidance for Cloud Systems) at https://csrc.nist.gov/
- Review any NIST cloud security publications that address data management specifically

**CDO Council:**
- Check whether the CDO Council has published any cloud data governance guidance not currently on the site

**OMB:**
- Review OMB M-19-19 (Data Center Optimization Initiative) which is already listed — determine if newer cloud-related OMB guidance exists that is not yet listed

## Recommended approach
Rather than creating a single new page, add two to three well-chosen resource listings that together give a practitioner a starting point. Each listing should be added as a summary file in `pages/_summaries/` with the keywords `data-governance`, `data-security`, and `cloud` (create the `cloud` keyword if it does not already exist in the repo).

## How to verify
Search https://resources.data.gov for "cloud" and confirm new resources appear in results. Confirm they appear under https://resources.data.gov/categories/guidance or the appropriate category.