We moved the building of an initial entry `README.md` file functionality
form `bin/cvt-submission.sh` to a new `bin/gen-readme.sh` tool.
Add `bin/gen-readme.sh` VERSION "2.0.0 2025-06-16".
Update `bin/cvt-submission.sh` to ignore while running `chkentry(1)`,
any submission top level `REDAME.md` file.
Removed unused template file `template/entry/README_md`.
Changed `bin/cvt-submission.sh` allowed minimum `chkentry(1)` VERSION from "1.1.5"
to "2.0.5".
Changed `bin/cvt-submission.sh` VERSION from "2.0.5 2025-05-18"
to "2.1.0 2025-06-16".
Update sitemap.
Tested the above via `make gen_top_html timestamp` on macOS.
