docs(changelog): add #1442 fragment

changelog.d/1442-traffic-coverage-edges.md

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+- Keep Street Traffic's flow status honest at the edges. A few TomTom-matched
+  dots among hundreds rounded to 0% and read "(no matches)", and a few
+  simulated dots rounded to "100% cov"; coverage now stays within 1–99% while
+  both are shown (Aditya, @Rohilalala, #1442).