[Docs] Fix schema to replace "tag" by "ref"-filter (#1841)

#1820 followup

docs/docs/20-usage/20-pipeline-syntax.md

@@ -347,15 +347,15 @@ when:
 
 [Read more about cron](./45-cron.md)
 
-#### `tag`
+#### `ref`
 
-This filter only applies to tag events.
-Use glob expression to execute a step if the tag name starts with `v`:
+The `ref` filter compares the git reference against which the pipeline is executed.
+This allows you to filter, for example, tags that must start with **v**:
 
 ```yaml
 when:
-  - event: tag
-    tag: v*
+  event: tag
+  ref: refs/tags/v*
 ```
 
 #### `status`
@@ -834,7 +834,7 @@ when:
 The `ref` filter compares the git reference against which the pipeline is executed.
 This allows you to filter, for example, tags that must start with **v**:
 
-```diff
+```yaml
 when:
   event: tag
   ref: refs/tags/v*

pipeline/schema/.woodpecker/test-when.yml

@@ -27,12 +27,12 @@ steps:
     when:
       event: [push, pull_request, tag, deployment]
 
-  when-tag:
+  when-ref:
     image: alpine
     commands:
       - echo "test"
     when:
-      tag: "v**"
+      ref: "refs/tags/v**"
 
   when-status:
     image: alpine

pipeline/schema/schema.json

@@ -139,8 +139,8 @@
             }
           ]
         },
-        "tag": {
-          "description": "Read more: https://woodpecker-ci.org/docs/usage/pipeline-syntax#tag",
+        "ref": {
+          "description": "Read more: https://woodpecker-ci.org/docs/usage/pipeline-syntax#ref",
           "type": "string"
         },
         "cron": {
@@ -289,8 +289,8 @@
             }
           ]
         },
-        "tag": {
-          "description": "Read more: https://woodpecker-ci.org/docs/usage/pipeline-syntax#tag",
+        "ref": {
+          "description": "Read more: https://woodpecker-ci.org/docs/usage/pipeline-syntax#ref",
           "type": "string"
         },
         "cron": {