doc/go1.5.txt: go generate: add $GOLINE

Change-Id: I9968ce162996e71843eeaf9764d216c401427fed
Reviewed-on: https://go-review.googlesource.com/9040Reviewed-by: Rob Pike <r@golang.org>

doc/go1.5.txt

@@ -62,6 +62,7 @@ cmd/go: add $DOLLAR to generate's variables (https://golang.org/cl/8091)
 cmd/go: std wildcard now excludes commands in main repo (https://golang.org/cl/5550)
 cmd/go: .swig/.swigcxx files now require SWIG 3.0.6 or later
 cmd/go: add -run flag to go generate (https://golang.org/cl/9005)
+cmd/go: add $GOLINE to generate's variables (https://golang.org/cl/9007)
 cmd/vet: better validation of struct tags (https://golang.org/cl/2685)
 cmd/ld: no longer record build timestamp in Windows PE file header (https://golang.org/cl/3740)
 cmd/go: add -toolexec build option