Markdown renderers emit 'use --json for the full row' but --json was removed in favor of --format json #20

Two markdown renderers emit a footer that references the long-gone --json shortcut:

cmd/format.go::renderServings:

fmt.Fprintln(w, \"_zero-valued nutrients omitted; use --json for the full row_\")

cmd/format.go::renderNutrition:

fmt.Fprintln(w, \"_zero-valued nutrients omitted; use --json for the full row_\")

Commit 054064e feat!: drop --json shortcut, default --format to \"markdown\" deliberately removed the --json flag in favor of --format json, but this inline help string was missed. An LLM or human following the suggestion verbatim now hits:

$ /tmp/crono-export servings --since today --json
error: unknown flag: --json

Expected: change both messages to read "use --format json for the full row" (and grep the rest of the codebase for similar stragglers — prime text and README look fine, but the inline strings are wrong).

Severity: minor