Glossary termify component shadowing and shadowing and update definition

Author: stevepiercy

docs/glossary.md

@@ -182,9 +182,17 @@ Configuration registry
     
     In Plone core, [`plone.app.registry`](https://pypi.org/project/plone.app.registry/) provides Plone UI and `GenericSetup` integration for [`plone.registry`](https://pypi.org/project/plone.registry/), which in turn implements a configuration registry for Zope applications.
 
-Shadowing (Volto)
-    Webpack provides an "alias" mechanism, where the path for a module can be aliased to another module.
-    By using this mechanism Volto enables customization (file overrides), similar to `z3c.jbot.`
+component shadowing
+shadowing
+    Volto uses a technique called component shadowing to override an existing Volto component with our local custom version, without having to modify Volto's source code. 
+
+    Volto's source components are located in the filepath stem of `omelette/src/components/`.
+    Custom components that shadow Volto's source would be located in the filepath stem of `src/customizations/components/`.
+    Shadow components would have the same filepath as Volto's source compenents, excluding the stem.
+    Thus `omelette/src/components/theme/Header/Header.jsx` would be shadowed by `src/customizations/components/theme/Header/Header.jsx`.
+
+    Webpack provides an alias mechanism that allows component shadowing in Volto, where the path for a module can be aliased to another module.
+    By using this mechanism of file overrides, or component shadowing, Volto enables customization, similar to `z3c.jbot.`
 
 Razzle
     A tool that simplifies SPA and SSR configuration for React projects.