Replace md5 checksum to sha256 checksum on download page

[chlorodose]

Is your feature request related to a problem? Please describe.
I noticed that the download page for mohist only provides an md5 checksum, but md5 has been cracked and cannot ensure the security of the file.

Describe the solution you'd like
Replace md5 checksum to sha256 or sha512.

Additional context
Add any other context or screenshots about the feature request here.