Documentation for pylint-dev#3995

Signed-off-by: Stavros Ntentos <[email protected]>

doc/user_guide/usage/output.rst

@@ -21,6 +21,19 @@ a colorized report to stdout at the same time:
 
   --output-format=json:somefile.json,colorized
 
+Environment Variables
+''''''''''''''''''''''''''''
+The colorization of the output can also be controlled through environment
+variables. The precedence for determining output format is as follows:
+
+1. ``NO_COLOR``
+2. ``FORCE_COLOR``, or ``PY_COLORS``
+3. ``--output-format=...``
+
+Setting ``NO_COLOR`` (to any value) will disable colorized output, while
+``FORCE_COLOR`` or ``PY_COLORS`` (to any value) will enable it, overriding
+the ``--output-format`` option if specified.
+
 
 Custom message formats
 ''''''''''''''''''''''