Add default page to categories (#2869)

docs/docs/20-usage/51-plugins/_category_.yml

@@ -2,3 +2,6 @@ label: 'Plugins'
 # position: 2
 collapsible: true
 collapsed: true
+link:
+  type: 'doc'
+  id: 'plugins'

docs/docs/30-administration/00-deployment/00-overview.md

@@ -1,4 +1,4 @@
-# Overview
+# Deployment
 
 A Woodpecker deployment consists of two parts:
 

docs/docs/30-administration/00-deployment/_category_.yml

@@ -1,3 +1,6 @@
 label: 'Deployment'
 collapsible: true
 collapsed: true
+link:
+  type: 'doc'
+  id: 'overview'

docs/docs/30-administration/11-forges/10-overview.md

@@ -1,4 +1,4 @@
-# Overview
+# Forges
 
 ## Supported features
 

docs/docs/30-administration/11-forges/_category_.yml

@@ -1,3 +1,6 @@
 label: 'Forges'
 collapsible: true
 collapsed: true
+link:
+  type: 'doc'
+  id: 'overview'