chore(influxdb3): Overhaul processing engine guide:

- Explain the relationship between trigger specs and plugin function signatures
- Use more examples
- Add clear steps

Author: jstirnaman

content/influxdb3/core/plugins.md

@@ -7,14 +7,13 @@ menu:
   influxdb3_core:
     name: Processing engine and Python plugins
 weight: 4
-influxdb3/core/tags: []
+influxdb3/core/tags: [processing engine, python]
 related:
 - /influxdb3/core/reference/cli/influxdb3/test/wal_plugin/ 
-- /influxdb3/core/reference/cli/influxdb3/create/plugin/ 
 - /influxdb3/core/reference/cli/influxdb3/create/trigger/
 source: /shared/v3-core-plugins/_index.md
 ---
 
 <!-- 
-The content of this page is at /shared/v3-core-plugins/_index.md
+//SOURCE - content/shared/v3-core-plugins/_index.md
 -->

content/influxdb3/enterprise/plugins.md

@@ -7,14 +7,13 @@ menu:
   influxdb3_enterprise:
     name: Processing Engine and Python plugins
 weight: 4
-influxdb3/core/tags: []
+influxdb3/enterprise/tags: [processing engine, python]
 related:
 - /influxdb3/enterprise/reference/cli/influxdb3/test/wal_plugin/ 
-- /influxdb3/enterprise/reference/cli/influxdb3/create/plugin/
 - /influxdb3/enterprise/reference/cli/influxdb3/create/trigger/
 source: /shared/v3-core-plugins/_index.md
 ---
 
 <!-- 
-The content of this page is at /shared/v3-core-plugins/_index.md
+//SOURCE - content/shared/v3-core-plugins/_index.md
 -->