[docs] clarify lock file insignificance for libs, closes #504

doc/01-basic-usage.md

@@ -98,7 +98,7 @@ After installing the dependencies, Composer writes the list of the exact
 versions it installed into a `composer.lock` file. This locks the project
 to those specific versions.
 
-**Commit your project's `composer.lock` (along with `composer.json`) into version control.**
+**Commit your application's `composer.lock` (along with `composer.json`) into version control.**
 
 This is important because the `install` command checks if a lock file is present,
 and if it is, it downloads the versions specified there (regardless of what `composer.json`
@@ -115,6 +115,10 @@ the lock file with the new version.
 
     $ php composer.phar update
 
+> **Note:** For your library you may commit the `composer.lock` file too, but it
+> will not have any effect on other projects that depend on it. See also
+> [Libraries - Lock file](02-libraries.md#lock-file).
+
 ## Packagist
 
 [Packagist](http://packagist.org/) is the main Composer repository. A Composer