Fix equation and limerick to be correct. NetBSD fixed this 14 years ago

(src/games/fortune/datfiles/fortunes2 1.7).

PR:		188714
Submitted by:	ksmakoto dd.iij4u.or.jp
Reviewed by:	Wolfram Alpha
MFC after:	3 days

games/fortune/datfiles/fortunes

@@ -570,15 +570,15 @@ writing.  Always pick on the correct idiom.  The adverb always follows
 the verb.  Last but not least, avoid cliches like the plague; seek
 viable alternatives.
 %
-	      1/2
+	      1/3
 	 /\(3)
 	 |     2			  1/3
 	 |    z dz cos(3 * PI / 9) = ln (e   )
 	 |
 	\/ 1
 
 The integral of z squared, dz
-From 1 to the square root of 3
+From 1 to the cube root of 3
 	Times the cosine
 	Of 3 PI over nine
 Is the log of the cube root of e