Appdata file fails appdata-validate check
The appdata file added in 3.1.1 fails appdata-validate checks:
$ appdata-validate --relax --nonet kid3.appdata.xml
kid3.appdata.xml 2 problems detected:
? tag-missing : <metadata_license> is not present
? style-invalid : Not enough <p> content before <ul>
Imported from SourceForge, author: scop