diff --git a/misc/requirements/README.md b/misc/requirements/README.md
index 66d9290ca..a02edc530 100644
--- a/misc/requirements/README.md
+++ b/misc/requirements/README.md
@@ -1,2 +1,18 @@
 This directory contains various `requirements` files which are used by `tox` to
 have reproducable tests with pinned versions.
+
+The files are generated based on unpinned requirements in `*.txt-raw` files.
+
+Those files can also contain some special commands:
+
+- Add an additional comment to a line: `#@ comment: <package> <comment here>`
+- Filter a line for requirements.io: `#@ filter: <package> <filter>`
+- Don't include a package in the output: `#@ ignore: <package>` (or multiple packages)
+
+Some examples:
+
+```
+#@ comment: mypkg blah blub
+#@ filter: mypkg != 1.0.0
+#@ ignore: mypkg, otherpkg
+```