fix various doc typos #3320
diff --git a/Doc/library/string.rst b/Doc/library/string.rst
index fa953f2..be9bccb 100644
--- a/Doc/library/string.rst
+++ b/Doc/library/string.rst
@@ -293,7 +293,7 @@
 
    "noses     "
    
-Which is subsitituted into the string, yielding::
+Which is substituted into the string, yielding::
    
    "A man with two noses     "