Doc: improve documentation for working with template files

[bigon]

What version of Go, VS Code & VS Code Go extension are you using?

Version Information

• Run go version to get version of Go from the VS Code integrated terminal.
  • go version go1.23.4 linux/amd64
• Run gopls -v version to get version of Gopls from the VS Code integrated terminal.
  • v0.17.1
• Run code -v or code-insiders -v to get version of VS Code or VS Code Insiders.
  • 1.96.2
• Check your installed extensions to get the version of the VS Code Go extension
  • 0.44.0
• Run Ctrl+Shift+P (Cmd+Shift+P on Mac OS) > Go: Locate Configured Go Tools command.

  • Tools Configuration

Environment

GOBIN: undefined toolsGopath: gopath: /home/bigon/go GOROOT: /usr/lib/go-1.23 PATH: /home/bigon/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games

Tools

go:	/usr/bin/go: go version go1.23.4 linux/amd64

gopls:	/home/bigon/go/bin/gopls	(version: v0.17.1 built with go: go1.23.4)
gotests:	not installed
gomodifytags:	not installed
impl:	not installed
goplay:	not installed
dlv:	/usr/bin/dlv	(version: undefined built with go: go1.23.4)
staticcheck:	/home/bigon/go/bin/staticcheck	(version: v0.5.1 built with go: go1.23.4)

Go env

Workspace Folder (thanos-receivers): /home/bigon/Boulot//code/thanos-receivers

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/bigon/.cache/go-build'
GOENV='/home/bigon/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/bigon/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/bigon/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/lib/go-1.23'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/lib/go-1.23/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.23.4'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/bigon/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/dev/null'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build2302377950=/tmp/go-build -gno-record-gcc-switches'

Share the Go related settings you have added/edited

Default config

Describe the bug

No syntax highlighting for gotmpl

I'm expecting to have some colors and highlighting

Steps to reproduce the behavior:

1. Install the vscode-go extension
2. Open a gotmpl file
3. No syntax highlighting for gotmpl

Screenshots or recordings

If applicable, add screenshots or recordings to help explain your problem.