Update help messages of CLI commands

Author: lbarcziova

docs/cli/build/in-copr.md

@@ -42,6 +42,9 @@ for more details). Alternatively you can use copr API token available [here](htt
       PATH_OR_URL argument is a local path or a URL to the upstream git
       repository, it defaults to the current working directory.
 
+      Copr configuration needs to be set before usage.
+      https://docs.pagure.org/copr.copr/user_documentation.html#quick-start
+
     Options:
       --wait / --no-wait              Wait for the build to finish
       --owner TEXT                    Copr user, owner of the project. (defaults

docs/cli/validate-config.md

@@ -10,17 +10,4 @@ Validate the Packit configuration file.
 
 ## Help
 
-    Usage: packit validate-config [OPTIONS] [PATH_OR_URL]
 
-      Validate PackageConfig.
-
-      - checks missing values
-      - checks incorrect types
-      - checks whether monitoring is enabled if 'pull_from_upstream` is used
-
-      PATH_OR_URL argument is a local path or a URL to a git repository with
-      packit configuration file
-
-    Options:
-      --offline   Do not make remote API calls requiring network access.
-      -h, --help  Show this message and exit.