docs(website): explain the meaning of the caret symbol (lerna#3454)

website/docs/concepts/task-pipeline-configuration.md

@@ -79,6 +79,8 @@ This mechanism is very flexible. Let's look at this example:
 > Note, older versions of Nx used targetDependencies instead of targetDefaults. Both still work, but targetDefaults is
 > recommended.
 
+The `^` symbol (a.k.a the caret symbol) simply means dependencies. Therefore whereas `"test": { "dependsOn": ["build"] }` means a particular project's "test" target depends on its own "build" target to have already completed before running, `"build": { "dependsOn": ["^build"] }` means that a particular project's "build" target depends on the "build" target of all of the project's dependencies to have already completed before running.
+
 When running `lerna run test --scope=myproj`, the above configuration would tell Lerna to
 
 1. Run the `test` command for `myproj`