doc/go1.5.txt: new format for flag.PrintDefaults

Change-Id: Ic78deaf91b437016b0a064c1f9ef49c9c29f4c32
Reviewed-on: https://go-review.googlesource.com/7510Reviewed-by: Rob Pike <r@golang.org>

doc/go1.5.txt

@@ -13,6 +13,7 @@ crypto/elliptic: add Name field to CurveParams struct (https://golang.org/cl/213
 crypto/tls: change default minimum version to TLS 1.0. (https://golang.org/cl/1791)
 crypto/x509: wildcards are now only accepted as the first label (https://golang.org/cl/5691)
 encoding/base64: add unpadded encodings (https://golang.org/cl/1511)
+flag: new nicer format for PrintDefaults (https://go-review.googlesource.com/7330)
 go/ast: add Implicit field to ast.EmptyStmt; changed meaning of ast.EmptyStmt.Semicolon position (https://golang.org/cl/5720)
 log: add SetOutput functions (https://golang.org/cl/2686, https://golang.org/cl/3023)
 net/http: support for setting trailers from a server Handler (https://golang.org/cl/2157)