docs: Add preview environment address to l10n guide.

Created by: patrickluoyu

Signed-off-by: Patrick-LuoYu patrickluo@yunify.com

What type of PR is this?

/kind documentation

What this PR does / why we need it:

Add preview environment address to l10n guide.

Which issue(s) this PR fixes:

Fixes ## 2559

Special notes for reviewers:

/assign @harrisonliu5 @xuliwenwenwen @FeynmanZhou Please take a look. Thanks!

Does this PR introduced a user-facing change?

None