update docs

doc/src/manual/code-loading.md

@@ -351,7 +351,7 @@ Since the primary environment is typically the environment of a project you're w
 
 ### [Package Extensions](@id man-extensions)
 
-A package "extension" is a module that is automatically loaded when a specified set of other packages (its "extension dependencies") are loaded in the current Julia session. Extensions are defined under the `[extensions]` section in the project file. The extension dependencies of an extension are a subset of those packages listed under the `[weakdeps]` section of the project file. Those packages can have compat entries like other packages.
+A package "extension" is a module that is automatically loaded when a specified set of other packages (its "triggers") are loaded in the current Julia session. Extensions are defined under the `[extensions]` section in the project file. The triggers of an extension are a subset of those packages listed under the `[weakdeps]` (and possibly, but uncommonly the `[deps]`) section of the project file. Those packages can have compat entries like other packages.
 
 ```toml
 name = "MyPackage"
@@ -371,27 +371,27 @@ FooExt = "ExtDep"
 ```
 
 The keys under `extensions` are the names of the extensions.
-They are loaded when all the packages on the right hand side (the extension dependencies) of that extension are loaded.
-If an extension only has one extension dependency the list of extension dependencies can be written as just a string for brevity.
+They are loaded when all the packages on the right hand side (the triggers) of that extension are loaded.
+If an extension only has one trigger the list of triggers can be written as just a string for brevity.
 The location for the entry point of the extension is either in `ext/FooExt.jl` or `ext/FooExt/FooExt.jl` for
 extension `FooExt`.
 The content of an extension is often structured as:
 
 ```
 module FooExt
 
-# Load main package and extension dependencies
+# Load main package and triggers
 using MyPackage, ExtDep
 
-# Extend functionality in main package with types from the extension dependencies
+# Extend functionality in main package with types from the triggers
 MyPackage.func(x::ExtDep.SomeStruct) = ...
 
 end
 ```
 
 When a package with extensions is added to an environment, the `weakdeps` and `extensions` sections
 are stored in the manifest file in the section for that package. The dependency lookup rules for
-a package are the same as for its "parent" except that the listed extension dependencies are also considered as
+a package are the same as for its "parent" except that the listed triggers are also considered as
 dependencies.
 
 ### [Workspaces](@id workspaces)