minor #16265 Correct spelling & grammar in 4.4 components/yaml/ (gnito-org)

This PR was merged into the 4.4 branch.

Discussion
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Correct spelling & grammar in 4.4 components/yaml/

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Commits
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0df55fc Correct spelling & grammar in 4.4 components/yaml/

Author: javiereguiluz

components/yaml/yaml_format.rst

@@ -25,7 +25,7 @@ they can also be unquoted:
 
     A string in YAML
 
-    'A singled-quoted string in YAML'
+    'A single-quoted string in YAML'
 
     "A double-quoted string in YAML"