Repository: go
Issue: x/text/language/display: request to change British to UK
Labels: NeedsDecision

<!-- Please answer these questions before submitting your issue. Thanks! -->

### What version of Go are you using (`go version`)?

<pre>
$ go version
go version go1.12.1 linux/amd64
</pre>

### Does this issue reproduce with the latest release?
Yes, v0.3.0

### What operating system and processor architecture are you using (`go env`)?

<details><summary><code>go env</code> Output</summary><br><pre>
$ go env
go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/mhorn/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/mhorn/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/lib/golang"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/golang/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build634574407=/tmp/go-build -gno-record-gcc-switches"
</pre></details>

### What did you do?

Using "golang.org/x/text/language/display" tags to display the language name.

https://play.golang.org/p/kCvmNJvgrHO

I was asked to change the "British English" to "English (UK)", but I see a few others that seem to be "non-standard"?

Should I be using a different API for this format? Or has "text/language" fallen behind current updates?


### What did you expect to see?
<pre>
Tag Name                                 Language Name        (Display Name)
--------                                 -------------        (------------)
English (Antigua & Barbuda)              English              (English)
English (Australian)                     Australian English   (English)
English (Botswana)                       English              (English)
English (Canadian)                       Canadian English     (English)
English (UK)                             British English      (English)
English (Hong Kong SAR China)            English              (English)
English (Ireland)                        English              (English)
English (Israel)                         English              (English)
English (India)                          English              (English)
English (Nigeria)                        English              (English)
English (New Zealand)                    English              (English)
English (Philippines)                    English              (English)
English (Seychelles)                     English              (English)
English (Singapore)                      English              (English)
English (US)                             American English     (English)
English (South Africa)                   English              (English)
English (Zambia)                         English              (English)
English (Zimbabwe)                       English              (English)
</pre>

### What did you see instead?
<pre>
Tag Name                                 Language Name        (Display Name)
--------                                 -------------        (------------)
English (Antigua & Barbuda)              English              (English)
Australian English                       Australian English   (Australian English)
English (Botswana)                       English              (English)
Canadian English                         Canadian English     (Canadian English)
British English                          British English      (British English)
English (Hong Kong SAR China)            English              (English)
English (Ireland)                        English              (English)
English (Israel)                         English              (English)
English (India)                          English              (English)
English (Nigeria)                        English              (English)
English (New Zealand)                    English              (English)
English (Philippines)                    English              (English)
English (Seychelles)                     English              (English)
English (Singapore)                      English              (English)
American English                         American English     (American English)
English (South Africa)                   English              (English)
English (Zambia)                         English              (English)
English (Zimbabwe)                       English              (English)
</pre>