Re-apply documentation addition

Author: uranusjr

docs/html/cli/pip_freeze.rst

@@ -72,3 +72,21 @@ Examples
 
          env1\bin\python -m pip freeze > requirements.txt
          env2\bin\python -m pip install -r requirements.txt
+
+
+Fixing "Permission denied:" errors
+==================================
+
+The purpose of this section of documentation is to provide practical
+suggestions to users seeing a `"Permission denied" error <https://github.com/pypa/pip/issues/8418>`__ on ``pip freeze``.
+
+This error occurs, for instance, when the command is installed only for another
+user, and the current user doesn't have the permission to execute the other
+user's command.
+
+To solve that issue, you can try one of the followings:
+
+- Install the command for yourself (e.g. in your home directory).
+- Ask the system admin to allow this command for all users.
+- Check and correct the PATH variable of your own environment.
+- Check the `ACL (Access-Control List) <https://en.wikipedia.org/wiki/Access-control_list>`_ for this command.