Normalize headings re: downloading code and translations

Before:

* Each CMS chapter uses slightly different headings and anchors
  for the same conceptual steps.
* Several of them try to distinguish when you do/do-not need translations,
  but they're arbitrarily different.

After:

* Each CMS chapter uses the same headings and anchors.
* If there was a different anchor before, then that anchor is still valid (but it is no
  longer visible or primary).
* It still tries to distinguish when you do/do-not need translations, but
  the language is simpler and more consistent.