Revert "docs: promote SoftwareUpdater as easy tool to update Haiku." This reverts commit 6487273924. This reverts commit 8aab3a0d5e. -- The Userguide and Welcome Guide are written and managed in the Userguide Translator, not in the tree.
6487273924
8aab3a0d5e
(note from waddlesplash: fixed xml:lang tags, responsive viewport everywhere, CSS tweaks.)