Minor improvements to the SpaceBeforeCast sniff documentation

Suggestions made during the PR review process

Co-authored-by: Juliette <[email protected]>

Author: rodrigoprimo

src/Standards/Generic/Docs/Formatting/SpaceBeforeCastStandard.xml

@@ -1,7 +1,7 @@
-<documentation title="Space Before Casts">
+<documentation title="Space Before Cast">
     <standard>
     <![CDATA[
-    Ensures there is exactly one space before a cast operator.
+    There should be exactly one space before a cast operator.
     ]]>
     </standard>
     <code_comparison>