Merge pull request #2659 from nabim777/add-step-on-docs-for-manually-installation

add step on docs for manual installation

Author: vabene1111

docs/install/manual.md

@@ -24,6 +24,8 @@ Give the user permissions: `chown -R recipes:www-data /var/www/recipes`
 
 Create virtual env: `python3 -m venv /var/www/recipes`
 
+Activate virtual env: `source /var/www/recipes/bin/activate`
+
 Install Javascript Tools (nodejs >= 12 required)
 ```shell
 ### Just use one of these possibilites!