[3.9] [doc] Fix a typo in the graphlib docs (GH-22030) (GH-22076)



(cherry picked from commit 851606007665dc30089e5e1953208c5428e455b1)


Co-authored-by: Mario Šaško <mariosasko777@gmail.com>
diff --git a/Doc/library/graphlib.rst b/Doc/library/graphlib.rst
index 820615e..0faca21 100644
--- a/Doc/library/graphlib.rst
+++ b/Doc/library/graphlib.rst
@@ -121,7 +121,7 @@
           if ts.is_active():
               ...
 
-      if possible to simply do::
+      it is possible to simply do::
 
           if ts:
               ...