Add documentation on pip's role as an installer

docs/html/topics/index.md

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 secure-installs
 vcs-support
 python-option
+workflow
 ```

docs/html/topics/workflow.md

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+# Pip is not a workflow management tool
+
+The core purpose of pip is to *manage the packages installed in your
+environment*. Whilst package management is an important part of most Python
+development workflows, it is only one part. Tasks like creating and managing
+environments, configuring and running development tasks, managing the Python
+interpreter itself, and managing the overall "project", are not part of pip's
+scope. Managing a development workflow as a whole is a complex task and one
+where there are many views on the "correct approach".
+
+Pip has a number of features which make it useful in development workflows - for
+example, the ability to install the current project via `pip install .`,
+editable installs, and requirements files. However, there is no intention that
+pip will manage the workflow as a whole.
+
+As an example, pip provides the `pip wheel` command, which can be used to build
+a wheel for your project. However, there is no corresponding command to build a
+source distribution. This is because building a wheel is a fundamental step in
+installing a package (if that package is only available as source code), whereas
+building a source distribution is never needed when installing. Users who need a
+tool to build their project should use a dedicated tool like `build`, which
+provides commands to build wheels and source distributions.
+
+
+## The role of `ensurepip`
+
+Pip is available in a standard Python installation, via the `ensurepip` stdlib
+module. This provides users with an "out of the box" installer, which can be
+used to gain access to all of the various tools and libraries available on PyPI.
+In particular, this enables the installation of a number of workflow tools.
+
+This "bootstrapping" mechanism was proposed (and accepted) in [PEP
+453](https://peps.python.org/pep-0453/).
+
+
+## Further information
+
+The [Packaging User Guide](https://packaging.python.org) discusses Python
+project development, and includes tool recommendations for people looking for
+further information on how to manage their development workflow.