docs(mps-model-server-plugin): document available health checks

Author: languitar

docs/global/modules/core/pages/reference/component-mps-model-server-plugin.adoc

@@ -0,0 +1,25 @@
+= mps-model-server-plugin
+
+== Health checks
+
+The plugin offers a set of health checks via HTTP on port 48305 and path `/health`.
+Health checks can be enabled adding query parameters with the health check name and the value `true` to the request.
+
+=== indexer
+
+The check fails, if the indexer is currently running for one of the opened projects.
+
+[NOTE]
+====
+This check indicates a healthy system until a project is opened.
+Combine it with the `projects` health check to effectively wait for the system to be ready to serve data immediately.
+====
+
+=== projects
+
+Reports an unhealthy system whenever no project is loaded.
+
+=== virtualFolders
+
+Reports an unhealthy system when no virtual folders are available.
+This might also be true in case a project without virtual folders is fully loaded.

docs/global/modules/core/partials/nav-reference.adoc

@@ -4,3 +4,4 @@
 * xref:core:reference/component-model-api-gen.adoc[]
 * xref:core:reference/component-model-api-gen-gradle.adoc[]
 * xref:core:reference/component-light-model-client.adoc[]
+* xref:core:reference/component-mps-model-server-plugin.adoc[]