#46316 Issue: Update start.rst (#46335)

* #46316 Issue: Update start.rst

* Update start.rst

Added the link for detailed error

* Removed single ticks

docs/apache-airflow/start.rst

@@ -24,7 +24,7 @@ This quick start guide will help you bootstrap an Airflow standalone instance on
 
 .. note::
 
-   Successful installation requires a Python 3 environment. Starting with Airflow 2.7.0, Airflow supports Python 3.9, 3.10, 3.11 and 3.12.
+   Successful installation requires a Python 3 environment. Starting with Airflow 2.7.0, Airflow supports Python 3.9, 3.10, 3.11, and 3.12.
 
    Only ``pip`` installation is currently officially supported.
 
@@ -44,15 +44,36 @@ This quick start guide will help you bootstrap an Airflow standalone instance on
 The installation of Airflow is straightforward if you follow the instructions below. Airflow uses
 constraint files to enable reproducible installation, so using ``pip`` and constraint files is recommended.
 
-1. Set Airflow Home (optional):
+1. **(Recommended) Create and Activate a Virtual Environment**:
+
+   To avoid issues such as the ``externally-managed-environment`` error, particularly on modern Linux distributions like Ubuntu 22.04+ and Debian 12+, it is highly recommended to install Airflow inside a Python virtual environment. This approach prevents conflicts with system-level Python packages and ensures smooth installation.
+
+   For more details on this error, see the Python Packaging Authority's explanation in the `PEP 668 documentation <https://peps.python.org/pep-0668/>`_.
+
+   .. code-block:: bash
+
+      # Create a virtual environment in your desired directory
+      python3 -m venv airflow_venv
+
+      # Activate the virtual environment
+      source airflow_venv/bin/activate
+
+      # Upgrade pip within the virtual environment
+      pip install --upgrade pip
+
+      # Optional: Deactivate the virtual environment when done
+      deactivate
+
+2. **Set Airflow Home (optional)**:
 
    Airflow requires a home directory, and uses ``~/airflow`` by default, but you can set a different location if you prefer. The ``AIRFLOW_HOME`` environment variable is used to inform Airflow of the desired location. This step of setting the environment variable should be done before installing Airflow so that the installation process knows where to store the necessary files.
 
    .. code-block:: bash
 
       export AIRFLOW_HOME=~/airflow
 
-2. Install Airflow using the constraints file, which is determined based on the URL we pass:
+
+3. Install Airflow using the constraints file, which is determined based on the URL we pass:
 
    .. code-block:: bash
       :substitutions:
@@ -69,15 +90,15 @@ constraint files to enable reproducible installation, so using ``pip`` and const
 
       pip install "apache-airflow==${AIRFLOW_VERSION}" --constraint "${CONSTRAINT_URL}"
 
-3. Run Airflow Standalone:
+4. Run Airflow Standalone:
 
    The ``airflow standalone`` command initializes the database, creates a user, and starts all components.
 
    .. code-block:: bash
 
       airflow standalone
 
-4. Access the Airflow UI:
+5. Access the Airflow UI:
 
    Visit ``localhost:8080`` in your browser and log in with the admin account details shown in the terminal. Enable the ``example_bash_operator`` DAG in the home page.