(DOCSP-44793) Adds alternate download URL for network config. (#521)

Adds additional download URL to v7.0 docs. Once merged, backport to
v6.0.

- [DOCSP-44793](https://jira.mongodb.org/browse/DOCSP-44793)
-
[STAGING](https://deploy-preview-521--10gen-docs-ops-manager.netlify.app/core/requirements/#network-requirements)

### Self-Review Checklist

- [ ]
[Define](https://wiki.corp.mongodb.com/display/DE/Taxonomy+tagging+instructions)
taxonomy
[values](https://wiki.corp.mongodb.com/display/DE/Docs+Taxonomy) at top
of page.
- [ ] Add genre facets (tutorial or reference), as in this [example
PR](10gen/cloud-docs#5042).
- [ ] Add programmingLanguage (if necessary).
- [ ] Add meta keywords (if necessary).
- [ ] Resolve any new warnings or errors in the build.
- [ ] Proofread for spelling and grammatical errors.
- [ ] Check staging for rendering issues.
- [ ] Confirm links are working.

Author: erabil-mdb

source/includes/list-table-needed-mongodb-sites-over-internet.rst

@@ -4,7 +4,7 @@
 
    * - Site
      - Purpose
-   * - downloads.mongodb.com
+   * - downloads.mongodb.com, downloads.mongodb.org
      - To download :dl:`MongoDB Enterprise Builds <enterprise>`.
    * - opsmanager.mongodb.com
      - To download the MongoDB :opsmgr:`version manifest </reference/glossary/#std-term-version-manifest>`.