doc/go1.5.txt: time.AppendFormat

Change-Id: I9e8a0dc152ef9403ff5ece0c161bda3a2f4448a8
Reviewed-on: https://go-review.googlesource.com/8760Reviewed-by: Rob Pike <r@golang.org>

doc/go1.5.txt

@@ -45,6 +45,7 @@ syscall: Add Foreground and Pgid to SysProcAttr (https://golang.org/cl/5130)
 syscall: add missing Syscall9 for darwin/amd64 (https://golang.org/cl/6555)
 testing/quick: support generation of arrays (https://golang.org/cl/3865)
 text/template: add Options method (https://golang.org/cl/8462)
+time: add time.AppendFormat(https://golang.org/cl/1760)
 
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