fix truly evil markup typo
diff --git a/Doc/lib/libstring.tex b/Doc/lib/libstring.tex
index 950291c..11e31cf 100644
--- a/Doc/lib/libstring.tex
+++ b/Doc/lib/libstring.tex
@@ -221,7 +221,7 @@
words is the same as returned by \function{split()}, except when the
optional third argument \var{maxsplit} is explicitly specified and
nonzero. When \var{maxsplit} is nonzero, at most \var{maxsplit}
- number of splits -- the \em{rightmost} ones -- occur, and the remainder
+ number of splits -- the \emph{rightmost} ones -- occur, and the remainder
of the string is returned as the first element of the list (thus, the
list will have at most \code{\var{maxsplit}+1} elements).
\versionadded{2.4}