"build-essential" are needed for proper install on Linux

[rahul-ve]

On a fresh install of Windows Subsystem for Linux (Ubuntu 20.04), created a conda environment and tried to follow the above guide to install airflow but was getting gcc errors. Installing build-essential solved the issue.

On Windows 10, with a clean conda environment, setproctitle fails to install with error "Microsoft Visual C++ 14.0 is required". Suggests to install "Microsoft Visual C++ Build Tools". I got this both on Python version 3.8.3 and 3.5.6.
Installed some versions of C++ build tools from Visual Studio community edition installer and tried installing airflow again but getting a new error now - "cannot open include file: 'basetsd.h'".

May be add some prerequisites about Windows and Python versions?

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• [ x] Description above provides context of the change
• Unit tests coverage for changes (not needed for documentation changes)
• Target Github ISSUE in description if exists
• [ x] Commits follow "How to write a good git commit message"
• [ x] Relevant documentation is updated including usage instructions.
• [x ] I will engage committers as explained in Contribution Workflow Example.

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In case of fundamental code change, Airflow Improvement Proposal (AIP) is needed.
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In case of backwards incompatible changes please leave a note in UPDATING.md.
Read the Pull Request Guidelines for more information.

[boring-cyborg]

Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contribution Guide (https://github.com/apache/airflow/blob/master/CONTRIBUTING.rst)
Here are some useful points:

• Pay attention to the quality of your code (flake8, pylint and type annotations). Our pre-commits will help you with that.
• In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example DAG that shows how users should use it.
• Consider using Breeze environment for testing locally, it’s a heavy docker but it ships with a working Airflow and a lot of integrations.
• Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
• Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Mailing list and Slack.
• Be sure to read the Airflow Coding style.
  Apache Airflow is a community-driven project and together we are making it better 🚀.
  In case of doubts contact the developers at:
  Mailing List: dev@airflow.apache.org
  Slack: https://apache-airflow-slack.herokuapp.com/

[rahul-ve]

The two items unchecked do not apply in this case. Do they have to be checked?

[boring-cyborg]

Awesome work, congrats on your first merged pull request!