id: normalize with mdbook-i18n-helpers 0.2.2 (#1106)

Before, po/id.po had these statistics:

32 translated messages, 4 fuzzy translations, 1745 untranslated
messages.

Afterwards, the statistics for po/id.po is:

32 translated messages, 3 fuzzy translations, 2432 untranslated
messages.

The number of translated messages changed from 2% to 1%.

With this change, it becomes important to use the latest version of
mdbook-i18n-helpers when viewing the translation locally. To update to
the latest version, run

    cargo install mdbook-i18n-helpers

You will now be able to serve the translation locally.

Part of #330.