[docs] custom script examples, [build] move CMS make to app via event_handlers.on_build

docs/dev/docs.dev.custom_script.md

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+---
+{
+	"_label": "Custom Script Examples",
+	"_toc": [
+		"docs.dev.custom_script.fetch",
+		"docs.dev.custom_script.validate",
+		"docs.dev.custom_script.validate1",
+		"docs.dev.custom_script.validate2",
+		"docs.dev.custom_script.validate3",
+		"docs.dev.custom_script.read_only",
+		"docs.dev.custom_script.calculate",
+		"docs.dev.custom_script.item_code"
+	]
+}
+---
+### How to Create a Custom Script
+
+Create a Custom Script (you must have System Manager role for this):
+
+1. Got to: Setup > Custom Script > New Custom Script
+1. Select the DocType in which you want to add the Custom Script
+
+---
+### Notes
+
+1. Server Custom Scripts are only available for the Administrator.
+1. Client Custom Scripts are in Javascript and Server Custom Scripts are in Python.
+1. For testing, make sure to go to Tools > Clear Cache and refresh after updating a Custom Script.
+
+	
+