pw_tokenizer: GN integration for token databases

- Provide the pw_tokenizer_database template that updates a token
  database in the source tree from build artifacts or other token
  databases.
- Support paths or booleans for pw_python_script's stamp argument.

Change-Id: I11a35bb77d6cfa1f328986915e3f17e9603327a5
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/14586
Commit-Queue: Wyatt Hepler <hepler@google.com>
Reviewed-by: Alexei Frolov <frolv@google.com>
diff --git a/pw_build/docs.rst b/pw_build/docs.rst
index 05b31dc..c16eab1 100644
--- a/pw_build/docs.rst
+++ b/pw_build/docs.rst
@@ -97,9 +97,13 @@
 ``pw_python_script`` accepts all of the arguments of a regular ``action``
 target. Additionally, it has some of its own arguments:
 
-* ``stamp``: Optional boolean indicating whether to automatically create a dummy
-  output file for the script. This allows running scripts without specifying any
-  ``outputs``.
+* ``capture_output``: Optional boolean. If true, script output is hidden unless
+  the script fails with an error. Defaults to true.
+* ``stamp``: Optional variable indicating whether to automatically create a
+  dummy output file for the script. This allows running scripts without
+  specifying ``outputs``. If ``stamp`` is true, a generic output file is
+  used. If ``stamp`` is a file path, that file is used as a stamp file. Like any
+  output file, ``stamp`` must be in the build directory. Defaults to false.
 
 **Expressions**