Docs: Avoid linking to the old plugin guidelines

Ours are here now.

diff --git a/doc/05-service-monitoring.md b/doc/05-service-monitoring.md
index c6940e0bff3ad89cf484874119e3f718bef6cb91..84d8a49c0b99af8b4c6e70ea1c79d33d03844600 100644 (file)
--- a/doc/05-service-monitoring.md
+++ b/doc/05-service-monitoring.md
@@ -427,7 +427,7 @@ definitions.
 ### Plugin API <a id="service-monitoring-plugin-api"></a>
 
 Icinga 2 supports the native plugin API specification from the Monitoring Plugins project.
-It is defined in the [Monitoring Plugins Development Guidelines](https://www.monitoring-plugins.org/doc/guidelines.html).
+It is defined in the [Monitoring Plugins](https://www.monitoring-plugins.org) guidelines.
 
 The Icinga documentation revamps the specification into our
 own guideline enriched with examples and best practices.