versionlock: Document that local packages are not affected

Local packages are added to a sack after the versionlock plugin logic
runs, so the plugin cannot exclude them from an installation.

This patch documents this deficiency.

Resolve: #585
Resolve: https://issues.redhat.com/browse/RHEL-94014
Resolve: https://issues.redhat.com/browse/RHEL-94828

Author: ppisar

doc/versionlock.rst

@@ -47,6 +47,9 @@ excludes a package that matches the version exactly.
 Note the versionlock plugin does not apply any excludes in non-transactional
 operations like `repoquery`, `list`, `info`, etc.
 
+Note that the versionlock plugin only applies to in-repository packages.
+Packages passed on the DNF command line as local files won't be affected.
+
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 Synopsis
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