Update pyproject.md (#2829)

* Update pyproject.md

Explain that `poetry install` installs the scripts in the virtualenv. See #2179 for the use case.

docs/docs/pyproject.md

@@ -216,6 +216,10 @@ poetry = 'poetry.console:run'
 
 
 Here, we will have the `poetry` script installed which will execute `console.run` in the `poetry` package.
 Here, we will have the `poetry` script installed which will execute `console.run` in the `poetry` package.
 
 
+!!!note
+
+    When a script is added or updated, run `poetry install` to make them available in the project's virtualenv.
+
 ## `extras`
 ## `extras`
 
 
 Poetry supports extras to allow expression of:
 Poetry supports extras to allow expression of: