More version doc updates

doc/articles/versions.md

@@ -2,7 +2,7 @@
     tagline: Versions explained.
 -->
 
-# Versions
+# Versions and constraints
 
 ## Composer Versions vs VCS Versions
 
@@ -84,7 +84,7 @@ When branch names look like versions, we have to clarify for composer that we're
 
 There's one more thing that will affect which files are checked out of a library's VCS and added to your project: Composer allows you to specify stability constraints to limit which tags are considered valid. In the above example, note that the library released a beta and two release candidates for version `1.1` before the final official release. To receive these versions when running `composer install` or `composer update`, we have to explicitly tell Composer that we are ok with release candidates and beta releases (and alpha releases, if we want those). This can be done using either a project-wide `minimum-stability` value in `composer.json` or using "stability flags" in version constraints. Read more on the [schema page](../04-schema.md#minimum-stability).
 
-## Writing Basic Version Constraints
+## Writing Version Constraints
 
 Now that you have an idea of how Composer sees versions, let's talk about how
 to specify version constraints for your project dependencies.