x/website: document modules/gomod-ref missing godebug introduced in go 1.23

[haitch]

Go version

1.23

Output of go env in your module/workspace:

n/a

What did you do?

research godebug syntax in go.mod reference https://go.dev/doc/modules/gomod-ref

What did you see happen?

not seeing this godebug in the doc at all.

What did you expect to see?

it appears to be introduced in go 1.23: https://go.dev/doc/godebug#default , which are missing in gomod-ref document

[mknyszek]

CC @golang/tools-team

[hyangah]

cc @matloob @samthanawalla

[gopherbot]

Change https://go.dev/cl/618115 mentions this issue: _content/doc/modules: document godebug directive in go.mod