Codex code review flagged that external templates copied from pre-rename
versions of the repo still reference the misspelled SECTION_SEPERATOR
helper. Despite pi-utils compiling with `strict: false`, Handlebars
still throws "Missing helper" on unknown helpers in that mode
(verified: `strict: false` only silences missing context variables,
not missing helpers), so renaming alone would break live user configs
at render time.
Registers the legacy `SECTION_SEPERATOR` name as a second alias to the
same implementation so both spellings render identically. The canonical
spelling `SECTION_SEPARATOR` is used in all in-tree templates; the
alias exists purely for backward compatibility with external templates.
Miroslav Drbal
3408b954bf