fix doc build warning

t20100 · t20100 · commit 3d1fe0cc34c0 · 2026-01-16T14:06:19.000+01:00
diff --git a/doc/usage.rst b/doc/usage.rst
@@ -103,7 +103,7 @@ Sperr
    :undoc-members:
 
 SZ
-==
+===
 
 .. autoclass:: SZ
    :members:
