dt-bindings: example: Grammar improvements

Improve grammar in recently added sentences:
  - Drop superfluous "be" in front of "have",
  - Add missing articles.

Fixes: 73f76a41c4 ("dt-bindings: example: Extend based on practice")
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200925111429.3146-1-geert+renesas@glider.be
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/example-schema.yaml

@@ -81,7 +81,7 @@ properties:
     maxItems: 1
     description: bus clock. A description is only needed for a single item if
       there's something unique to add.
-      The items should be have a fixed order, so pattern matching names are
+      The items should have a fixed order, so pattern matching names are
       discouraged.
 
   clock-names:
@@ -99,7 +99,7 @@ properties:
       A variable number of interrupts warrants a description of what conditions
       affect the number of interrupts. Otherwise, descriptions on standard
       properties are not necessary.
-      The items should be have a fixed order, so pattern matching names are
+      The items should have a fixed order, so pattern matching names are
       discouraged.
 
   interrupt-names:
@@ -226,8 +226,8 @@ allOf:
 # This can't be used in cases where another schema is referenced
 # (i.e. allOf: [{$ref: ...}]).
 # If and only if another schema is referenced and arbitrary children nodes can
-# appear, "unevaluatedProperties: false" could be used.  Typical example is I2C
-# controller where no name pattern matching for children can be added.
+# appear, "unevaluatedProperties: false" could be used.  A typical example is
+# an I2C controller where no name pattern matching for children can be added.
 additionalProperties: false
 
 examples: