doc: typo Synopis

%s/Synopis/Synopsis/g

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/doc/usage/cmd/sf.rst b/doc/usage/cmd/sf.rst
index 24d5dc6..dfdca46 100644
--- a/doc/usage/cmd/sf.rst
+++ b/doc/usage/cmd/sf.rst
@@ -6,8 +6,8 @@
 sf command
 ==========
 
-Synopis
--------
+Synopsis
+--------
 
 ::