cmd/go/internal/bug: sync issue body format with GitHub template

[myitcv]

go bug populates a Github issue in the order below, as opposed to https://github.com/golang/go/blob/b8669ef1ceabd386b58a99b4e2f4e67915fec428/.github/ISSUE_TEMPLATE

Not critical clearly but maybe nice to bring in line? cc @andybons?

---

Please answer these questions before submitting your issue. Thanks!

What did you do?

If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is best.

What did you expect to see?

What did you see instead?

Does this issue reproduce with the latest release (go1.10.3)?

System details

go version devel +6b9c782f9f Wed Aug 1 00:57:00 2018 +0000 linux/amd64
GOARCH="amd64"
GOBIN="/home/myitcv/.mountpoints/x/src/myitcv.io/.bin"
GOCACHE="/home/myitcv/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/myitcv/.mountpoints/x"
GOPROXY=""
GORACE=""
GOROOT="/home/myitcv/gos"
GOTMPDIR=""
GOTOOLDIR="/home/myitcv/gos/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/myitcv/.mountpoints/x/src/myitcv.io/go.mod"
GOROOT/bin/go version: go version devel +6b9c782f9f Wed Aug 1 00:57:00 2018 +0000 linux/amd64
GOROOT/bin/go tool compile -V: compile version devel +6b9c782f9f Wed Aug 1 00:57:00 2018 +0000
uname -sr: Linux 4.15.0-29-generic
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.1 LTS
Release:	18.04
Codename:	bionic
/lib/x86_64-linux-gnu/libc.so.6: GNU C Library (Ubuntu GLIBC 2.27-3ubuntu1) stable release version 2.27.

[andybons]

Really good first bug for anyone interested. Thanks for the report, Paul!

[joshblakeley]

Working on this

[gopherbot]

Change https://golang.org/cl/127495 mentions this issue: cmd/go: update go bug to be consistent with Github issue template

[darkLord19]

Is this issue still open?

[myitcv]

Yes @joshblakeley is working on this

[dmitshur]

@joshblakeley Please take the latest changes to the GitHub issue template in CL 138295 into account (see #28583 for more background).

Adding release-blocker label so we don't forget about this issue, I'd like it to get into 1.12.