Clarify quick start step and link to Breeze doc in MySQL error (#21552)

CONTRIBUTORS_QUICK_START.rst

@@ -317,10 +317,14 @@ Installing airflow in the local virtual environment ``airflow-env`` with breeze.
 .. code-block:: bash
 
   $ sudo apt-get install sqlite libsqlite3-dev default-libmysqlclient-dev postgresql
-  $ ./breeze initialize-local-virtualenv --python 3.8
 
+2. Initialize virtual environment with breeze.
 
-2. Add following line to ~/.bashrc in order to call breeze command from anywhere.
+.. code-block:: bash
+
+  $ ./breeze initialize-local-virtualenv --python 3.8
+
+3. Add following line to ~/.bashrc in order to call breeze command from anywhere.
 
 .. code-block:: bash
 
@@ -421,6 +425,9 @@ Using Breeze
    MySQL Workbench with Host ``127.0.0.1``, port ``23306``, user ``root`` and password
    blank(leave empty), default schema ``airflow``.
 
+   If you cannot connect to MySQL, refer to the Prerequisites section in the
+   |Breeze documentation| and try increasing Docker disk space.
+
    .. raw:: html
 
       <div align="center" style="padding-bottom:10px">