Align attribute template with applied conventions

During review and revision of the PRs applying the attribute template
to attributes in the Reference, we've established several standard
phrasings.  We had earlier updated the attribute template for most of
these.  But for some, we hadn't yet.  Let's align the template with
four of these actual conventions.
diff --git a/dev-guide/src/attributes.md b/dev-guide/src/attributes.md
index b47b2eb..2b6d082 100644
--- a/dev-guide/src/attributes.md
+++ b/dev-guide/src/attributes.md
@@ -50,7 +50,7 @@
 
 ----
 
-The `example` attribute has the following forms:
+The `example` attribute has these forms:
 
 - [MetaWord]
   > [!EXAMPLE]
@@ -106,7 +106,7 @@
 
 ----
 
-The `example` attribute is allowed anywhere attributes are allowed.
+The `example` attribute may be used anywhere attributes are allowed.
 
 ----
 
@@ -118,7 +118,7 @@
 ----
 
 r[PARENT.example.duplicates]
-Explain the behavior when the attribute is specified multiple times on an element. See [`AttributeDuplicates`](https://github.com/rust-lang/rust/blob/40d2563ea200f9327a8cb8b99a0fb82f75a7365c/compiler/rustc_feature/src/builtin_attrs.rs#L143) in the compiler. Examples:
+Explain the behavior when the attribute is used multiple times on an element. See [`AttributeDuplicates`](https://github.com/rust-lang/rust/blob/40d2563ea200f9327a8cb8b99a0fb82f75a7365c/compiler/rustc_feature/src/builtin_attrs.rs#L143) in the compiler. Examples:
 
 ----
 
@@ -155,7 +155,7 @@
 
 ----
 
-If the `example` attribute is used more than once on an item, then the combination of all the specified values is used as ...explain how they are merged.
+If the `example` attribute is used more than once on an item, then the combination of all listed values is used as ...explain how they are merged.
 
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