Fix Grammar

Fixed a grammatical error

docs/intro/data-availability.rst

@@ -10,7 +10,7 @@ or his application data from the cloud.
 In many ways, data availability has become a necessary precondition for an
 application to be considered "user friendly". Unfortunately, most applications
 attempt to provide high data availability by rolling their own custom solution
-or relying on a third party API, such as Dropbox. This approach is has several
+or relying on a third party API, such as Dropbox. This approach has several
 drawbacks: the user has no control or access to the data should they wish to
 switch applications or data providers; custom data synchronizations schemes are
 often an afterthought, poorly designed, and vulnerable to attack and data