Add selfupdate to the gvm help text.
Add selfupdate to the gvm help text.

skpal/sdkman-cli,DealerDotCom/gvm-cli,dsyer/gvm,gvmtool/gvm-cli,nobeans/gvm-cli,skpal/sdkman-cli,GsusRecovery/sdkman-cli,GsusRecovery/sdkman-cli,DealerDotCom/gvm-cli,nobeans/gvm-cli,shanman190/sdkman-cli,sdkman/sdkman-cli,jbovet/gvm,dsyer/gvm,busches/gvm-cli