minor #3896 Fixing comment typo for Doctrine findBy and findOneBy code example (beenanner)

This PR was merged into the 2.3 branch.

Discussion
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Fixing comment typo for Doctrine findBy and findOneBy code example

| Q                 | A
| --------------- | ---
| Doc fix?        | yes
| New docs?   | no
| Applies to     | all (or 2.3+)
| Fixed tickets | N/A

Commits
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a97991b Fixing comment typo for Doctrine findBy and findOneBy code example

Author: weaverryan

book/doctrine.rst

@@ -631,7 +631,7 @@ Once you have your repository, you have access to all sorts of helpful methods::
 You can also take advantage of the useful ``findBy`` and ``findOneBy`` methods
 to easily fetch objects based on multiple conditions::
 
-    // query for one product matching be name and price
+    // query for one product matching by name and price
     $product = $repository->findOneBy(
         array('name' => 'foo', 'price' => 19.99)
     );