Docs: Reverts non-English pages back to using "sdk" for page.template.

ag/783575 changed this value to "sdkl10n" with the intent of using a different
sdk template page for non-English files. This turns out to be unnecessary, and
it's better for all pages to be on the same sdkpage.cs template, so I'm reverting.

Change-Id: I2abba803cb77472f97ee5be074c2cac7d46ed643