docs(connectors): location inventory from asset connectors - #15838

Description

Adds a docs page for a new Pro feature: asset connectors can populate Location inventory directly on their mapped asset. A cloud connector maps an account to a Product, and the resources inside the account then appear as Locations on that Product. No finding needs to reference a resource first.

The page covers:

• how the sync fills the inventory in after asset reconciliation
• reconciliation rules: a missing resource goes to Mitigated and is never deleted, and a reappearing one returns to Active
• the flags that gate the feature (Connector Location Inventory + Locations, plus DD_CONNECTORS_ASSET_LOCATIONS on the connectors service)
• the per-record volume ceiling (DD_CONNECTORS_MAX_LOCATIONS_PER_RECORD, default 10,000)

Test results

Docs-only change, one new Markdown page under docs/content/connectors/upstream/. No code paths changed.

Documentation

This PR is the documentation.