Clean up Upstream schema refs in registry guides

Address Copilot review feedback on #873 by cleaning up missed
schema-qualifier references in the registry quickstart, operator
deployment guide, and skills guide.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: rdimitrov

docs/toolhive/guides-registry/deploy-operator.mdx

@@ -827,7 +827,7 @@ Common causes include:
 - **Source unavailable**: Git repository, API endpoint, or file is inaccessible
 - **Invalid JSON format**: Registry file contains invalid JSON
 - **Schema mismatch**: The data does not conform to the
-  [upstream MCP registry schema](../reference/registry-schema-upstream.mdx)
+  [ToolHive registry schema](../reference/registry-schema-upstream.mdx)
 - **Filter too restrictive**: Filters may be excluding all servers
 
 </details>

docs/toolhive/guides-registry/quickstart.mdx

@@ -21,7 +21,7 @@ ToolHive CLI and UI, see the [Introduction](./intro.mdx) for a comparison.
 - How to install the ToolHive Operator, which bundles the `MCPRegistry` CRD
 - How to deploy a minimal PostgreSQL database for the Registry Server
 - How to define registry data in a ConfigMap using the
-  [upstream MCP registry format](../reference/registry-schema-upstream.mdx)
+  [ToolHive registry format](../reference/registry-schema-upstream.mdx)
 - How to create an `MCPRegistry` resource that reads from that ConfigMap
 - How to query the Registry API
 
@@ -184,7 +184,7 @@ the Registry Server pod and points the server at it automatically when you set
 
 Define registry data in a ConfigMap. The Registry Server reads it through a
 file-based source. The ConfigMap uses the
-[upstream MCP registry format](../reference/registry-schema-upstream.mdx) with a
+[ToolHive registry format](../reference/registry-schema-upstream.mdx) with a
 single example server entry:
 
 ```yaml title="registry-data.yaml"

docs/toolhive/guides-registry/skills.mdx

@@ -15,7 +15,7 @@ Skills can come from two paths:
 - **Publish to a managed source via the admin API** (covered in depth below).
   Good for programmatic or UI-driven publishing with per-version control.
 - **Sync from external sources** (Git, upstream API, or file) that contain
-  skills in the upstream registry format. Good for catalogs that live in a
+  skills in the ToolHive registry format. Good for catalogs that live in a
   repository with code review and CI.
 
 For the file-based path, the registry JSON format is identical to the one used