Fix plugin documentation links in README.md and example plugins

Author: PierreRaybaut

README.md

@@ -36,7 +36,7 @@ Try DataLab online, without installing anything, using Binder:
 
 ----
 
-✨ Add features to DataLab by writing your own [plugin](https://datalab-platform.com/en/features/general/plugins.html)
+✨ Add features to DataLab by writing your own [plugin](https://datalab-platform.com/en/features/advanced/plugins.html)
 (see [plugin examples](https://github.com/DataLab-Platform/DataLab/tree/main/plugins/examples))
 or macro (see [macro examples](https://github.com/DataLab-Platform/DataLab/tree/main/macros/examples))
 

plugins/examples/datalab_custom_func.py

@@ -12,7 +12,7 @@
 
     This plugin is not installed by default. To install it, copy this file to
     your DataLab plugins directory (see `DataLab documentation
-    <https://datalab-platform.com/en/features/general/plugins.html>`_).
+    <https://datalab-platform.com/en/features/advanced/plugins.html>`_).
 """
 
 import numpy as np

plugins/examples/datalab_example_imageproc.py

@@ -13,7 +13,7 @@
 
     This plugin is not installed by default. To install it, copy this file to
     your DataLab plugins directory (see `DataLab documentation
-    <https://datalab-platform.com/en/features/general/plugins.html>`_).
+    <https://datalab-platform.com/en/features/advanced/plugins.html>`_).
 """
 
 import numpy as np