copy (or move?) license in a filename recognized by pkgsite

[dolmen]

The files containing the text of the license (Licence_CeCILL-B_V1-fr.txt, Licence_CeCILL-B_V1-en.txt) are not recognized by the pkgsite software which powers pkg.go.dev. As a result, sshproxy source code is not visible on pkg.go.dev. See for example https://pkg.go.dev/github.com/cea-hpc/sshproxy/cmd/sshproxy.

See list of recognized files at https://pkg.go.dev/license-policy

Note: CeCILL 2.1 license is correctly accepted with fixed issue 52126... if it is mentioned in a recognized file.