Fix install help message (lock file is prioritized) (#289)

poetry/console/commands/install.py

@@ -13,7 +13,7 @@ class InstallCommand(VenvCommand):
         { --develop=* : Install given packages in development mode. }
         { --develop=* : Install given packages in development mode. }
     """
     """
 
 
-    help = """The <info>install</info> command reads the <comment>pyproject.toml</> file from
+    help = """The <info>install</info> command reads the <comment>pyproject.lock</> file from
 the current directory, processes it, and downloads and installs all the
 the current directory, processes it, and downloads and installs all the
 libraries and dependencies outlined in that file. If the file does not
 libraries and dependencies outlined in that file. If the file does not
 exist it will look for <comment>pyproject.toml</> and do the same.
 exist it will look for <comment>pyproject.toml</> and do the same.