doc/go1.5.txt: add Jacobi and Int.ModSqrt to math/big

Change-Id: I187e97592cd0403d84ca25c4acb1a4b25495041b
Reviewed-on: https://go-review.googlesource.com/9534Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

doc/go1.5.txt

@@ -46,6 +46,7 @@ io: add CopyBuffer, Copy with user-provided buffer (https://golang.org/cl/8730)
 log: add SetOutput functions (https://golang.org/cl/2686, https://golang.org/cl/3023)
 log: add LUTC flag (https://golang.org/cl/8761)
 math/big: add arbitrary precision Floats (many cl's)
+math/big: add Jacobi and Int.ModSqrt (https://golang.org/cl/1886)
 mime: add ExtensionByType (https://golang.org/cl/7444)
 mime/quotedprintable: new package (https://golang.org/cl/5940 + others)
 net: add Source field to OpError (https://go-review.googlesource.com/9231)