rephrase slightly

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@1876 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

appendixa/flex-desc.xml

@@ -19,7 +19,7 @@ the text.</para></sect4>
 C++ scanners.</para></sect4>
 
 <sect4><title>lex</title>
-<para>We create a yacc script which calls flex using the -l option.
+<para>We create a bash script called lex which calls flex using the -l option.
 This is for compatibility purposes for programs which use lex instead
 of flex.</para></sect4>