For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ojkastl_buildservice:containers:helm-docs/15.6/home:ojkastl_buildservice:containers:helm-docs.repo
zypper refresh
zypper install helm-docs
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ojkastl_buildservice:containers:helm-docs/15.5/home:ojkastl_buildservice:containers:helm-docs.repo
zypper refresh
zypper install helm-docs
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ojkastl_buildservice:containers:helm-docs/15.4/home:ojkastl_buildservice:containers:helm-docs.repo
zypper refresh
zypper install helm-docs