added explanation for virtualenv vs docker (apache#16549)

added a paragraph on top, and made "Installing airflow in the local virtual environment" its own section to show that setting up the venv and setting up docker are two different methods, making this more beginner-friendly

CONTRIBUTORS_QUICK_START.rst

@@ -21,6 +21,22 @@ Contributor's Quick Guide
 
 .. contents:: :local:
 
+Note to Starters
+################
+
+There are two ways you can run the Airflow dev env on your machine:
+  1. With a Docker Container
+  2. With a local virtual environment
+Before deciding which method to choose, there are a couple factors to consider:
+Running Airflow in a container is the most reliable way: it provides a more consistent environment and allows integration tests with a number of integrations (cassandra, mongo, mysql, etc.). However it also requires **4GB RAM, 40GB disk space and at least 2 cores**.
+If you are working on a basic feature, installing Airflow on a local environment might be sufficient.
+
+- |Virtual Env Guide|
+
+.. |Virtual Env Guide| raw:: html
+
+   For a comprehensive venv tutorial - visit <a href="https://github.com/apache/airflow/blob/main/LOCAL_VIRTUALENV.rst"
+   target="_blank">Virtual Env Guide</a>
 
 Prerequisites
 #############
@@ -269,17 +285,18 @@ Setting up Breeze
 
   $ ./breeze stop
 
-6. Installing airflow in the local virtual environment ``airflow-env`` with breeze.
+Installing airflow in the local virtual environment ``airflow-env`` with breeze.
+--------------------------------------------------------------------------------
 
-   It may requires some packages to be installed, watch the output of the command to see which ones are missing.
+1. It may require some packages to be installed; watch the output of the command to see which ones are missing.
 
 .. code-block:: bash
 
   $ sudo apt-get install sqlite libsqlite3-dev default-libmysqlclient-dev postgresql
   $ ./breeze initialize-local-virtualenv --python 3.8
 
 
-7. Add following line to ~/.bashrc in order to call breeze command from anywhere.
+2. Add following line to ~/.bashrc in order to call breeze command from anywhere.
 
 .. code-block:: bash