v2021.4.540

• #213 - improve documentation for specifying created API key permissions (@liammclennan)
• #212 - fix alphabetical ordering of help headings (@nblumhardt)
• #146 - allow columns to be specified when creating signals (@samburville)
• #215 - use seqcli directly as the entrypoint when packaged for Docker (@nblumhardt)
• #217 - upgrade to .NET 6.0 (@KodrAus)
• #216 - support syntax annotations on Seq app setting definitions (@nblumhardt)
• #218 - fix the seqcli config command's -v option (@nblumhardt)