+NOTE: as of May 31, 2021 when Context Help was added, to include
+this Context Help you will need to download the corresponding
+tgz file containing the HTML manual sections referenced for the
+Help pages. The file to download is:
+\url{https://cinelerra-gg.org/download/images/HTML_Manual-20210531.tgz}
+substituting for "20210531" the "yyyymmdd" representing latest release date.
+Then unpack to your Cinelerra/bin/doc directory so it is included in
+your built system. The reason for not including the HTML manual in
+the source code so that it would already be there, is because it is
+very large and has its own GIT base.