minor symfony#9192 fix typo: continuting -> continuing (brizzz)

This PR was submitted for the 4.0 branch but it was merged into the 3.4 branch instead (closes symfony#9192).

Discussion
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fix typo: continuting -> continuing

Commits
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a584171 fix typo

Author: javiereguiluz

frontend/encore/versus-assetic.rst

@@ -51,6 +51,6 @@ Should I Upgrade from Assetic to Encore
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 If you already have Assetic working in an application, and haven't needed any of
-the features that Encore offers over Assetic, continuting to use Assetic is fine.
+the features that Encore offers over Assetic, continuing to use Assetic is fine.
 If you *do* start to need more features, then you might have a business case for
 changing to Encore.