[PATCH v2 07/49] perf python: Improve perf script -l descriptions

[Ian Rogers <irogers@google.com>]

Add module docstrings to counting.py, tracepoint.py, and twatch.py so
that 'perf script -l' displays concise descriptions for all available
standalone scripts:

```
$ perf script -l
List of available scripts:
...
  counting
    Example for counting perf events.
...
  tracepoint
    Example showing how to enable a tracepoint and access its fields.
  twatch
    Example to show how to enable a software event and track
    context switches.
...
```

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/python/counting.py   | 1 +
 tools/perf/python/tracepoint.py | 1 +
 tools/perf/python/twatch.py     | 1 +
 3 files changed, 3 insertions(+)

diff --git a/tools/perf/python/counting.py b/tools/perf/python/counting.py
index 02121d2bb11d..9adbbeccdacd 100755
--- a/tools/perf/python/counting.py
+++ b/tools/perf/python/counting.py
@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 # SPDX-License-Identifier: GPL-2.0
+"""Example for counting perf events."""
 # -*- python -*-
 # -*- coding: utf-8 -*-
 
diff --git a/tools/perf/python/tracepoint.py b/tools/perf/python/tracepoint.py
index 9d49a25b3b1e..faa5311b8418 100755
--- a/tools/perf/python/tracepoint.py
+++ b/tools/perf/python/tracepoint.py
@@ -1,5 +1,6 @@
 #! /usr/bin/env python
 # SPDX-License-Identifier: GPL-2.0
+"""Example showing how to enable a tracepoint and access its fields."""
 # -*- python -*-
 # -*- coding: utf-8 -*-
 
diff --git a/tools/perf/python/twatch.py b/tools/perf/python/twatch.py
index ad35b1620781..b0f1bf113162 100755
--- a/tools/perf/python/twatch.py
+++ b/tools/perf/python/twatch.py
@@ -1,5 +1,6 @@
 #! /usr/bin/env python
 # SPDX-License-Identifier: GPL-2.0-only
+"""Example to show how to enable a software event and track context switches."""
 # -*- python -*-
 # -*- coding: utf-8 -*-
 #   twatch - Experimental use of the perf python interface
-- 
2.55.0.1082.g2b9226bbc0-goog