docs: point cross-repo links to gitea instead of relative paths

Docs are rendered on a separate site (zensical), which only serves the
docs/ tree, so relative links out to config/services_registry.yml were
broken there. Point them at the Gitea file view instead. Left the
add-new-service.md -> ioc/iocs_overview.md link relative since it stays
within the docs tree.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A9GjKvXCmfgJpKzbQdZ7UA

docs/user/add-new-service.md

@@ -27,7 +27,7 @@ agebd service add --help
 clean working tree, then it:
 
 1. Assigns the service the next free IOC port and registers it in
-   [`config/services_registry.yml`](../../config/services_registry.yml).
+   [`config/services_registry.yml`](https://gitea.psi.ch/sls/hla_framework_bd/src/branch/main/config/services_registry.yml).
 2. Adds the service to `AGEBD-CPCL-MASTER`'s IOC pattern file, so it gets the standard
    ALH lifecycle PVs (`AGEBD-ALH$(SUFFIX):$(SERVICE)-*`) and appears in the `ServiceManager`
    GUI screen.

docs/user/ioc/iocs_overview.md

@@ -1,6 +1,6 @@
 # Overview of IOCs for Beam Dynamics
 
-The ports are configured in the [service registry](../../../config/services_registry.yml)
+The ports are configured in the [service registry](https://gitea.psi.ch/sls/hla_framework_bd/src/branch/main/config/services_registry.yml)
 
 | IOC NAME | Description |
 |---|---|