docs: fix long form of USDT to match acronym in python tutorial.
@@ -588,7 +588,7 @@ Things to learn:
### Lesson 15. nodejs_http_server.py
-This program instruments a user-defined static tracing (USDT) probe, which is the user-level version of a kernel tracepoint. Sample output:
+This program instruments a user statically-defined tracing (USDT) probe, which is the user-level version of a kernel tracepoint. Sample output:
```
# ./nodejs_http_server.py 24728
