feat(version): introduce version check subcommand

The version subcommand handles pkgver related commands, the first
subcommand being `check`. Check runs nvchecker if a `.nvchecker.toml`
file exists and compares the current pkgver with the latest release.

Introduces nvchecker as optional dependency which has to be installed in
order to use this particular subcommand.

BREAKING CHANGE: formerly pkgctl version would output the version of the
pkgctl tool, now it is used as a version related subcommand.

Fixes #140

Component: pkgctl version
Component: pkgctl version check
Co-authored-by: Christian Heusel <christian@heusel.eu>

1 files changed, 1 insertions, 1 deletions

diff --git a/doc/man/pkgctl.1.asciidoc b/doc/man/pkgctl.1.asciidoc
index 24b0613..929ae9a 100644
--- a/doc/man/pkgctl.1.asciidoc
+++ b/doc/man/pkgctl.1.asciidoc
@@ -51,7 +51,7 @@ pkgctl search::
 	Search for an expression across the GitLab packaging group
 
 pkgctl version::
-	Show pkgctl version information
+	Package version related commands
 
 See Also
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