feat: commit the corrected file of each platform

exports/ now holds the twelve platforms' own files, corrected, with a
report of every change, read by the site's corrected files page. Two
summaries are reworded for the page: an addition the format cannot
carry is counted as left out, and RetroPie names each skipped package
by sentence instead of joining reasons with semicolons. Its parser no
longer reads "e.g" as a file name.

scripts/siteexports.py

@@ -77,6 +77,11 @@ def generate_exports_page(reports: list[dict], names: dict[str, str]) -> str:
         "so a maintainer can diff it against theirs and take the changes "
         "line by line.",
         "",
+        "A file the emulators read and the list lacks is added only when the "
+        "format can carry it. Most platforms check an md5, so a file whose "
+        "source states no md5 is left out, and so is one filed under a system "
+        "the platform's checker never reads. Those are counted as left out.",
+        "",
     ]
     if not reports:
         lines.extend([