Changed guidance "Use a period only if the title is a full sentence." (carbon-design-system#3904)

* Changed guidance "Use a period only if the title is a full sentence."

In https://carbondesignsystem.com/components/notification/usage/, "Use a period only if the title is a full sentence." under Main elements > Title doesn't follow IBM Style, which is to not use punctuation on titles, so I revised the guidance as we discussed in the Feb6 Carbon Design Office Hours.

* chore: yarn format

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Co-authored-by: TJ Egan <tw15egan@gmail.com>
Co-authored-by: Alison Joseph <alison.joseph@us.ibm.com>

Author: 3 people

src/pages/components/notification/usage.mdx

@@ -119,7 +119,7 @@ apprised of the situation, and know what to do next.
 - The title should be short and descriptive, explaining the most important piece
   of information.
 - When possible, communicate the main message using just the title.
-- Use a period only if the title is a full sentence.
+- Don't use a period to end a title.
 - When using rich text, such as in a title, a screen reader will read aloud the
   entire message as one sentence. Since the message will be read as one string,
   make sure that any text styling does not convey meaning.

src/pages/components/radio-button/usage.mdx

@@ -102,8 +102,8 @@ buttons, a group label can be added.
 
 1. **Group label (optional):** Describes the group of options or provides
    guidance for making a selection.
-2. **Radio button input:** Indicates the state of a radio button. By
-   default, no option will be preselected.
+2. **Radio button input:** Indicates the state of a radio button. By default, no
+   option will be preselected.
 3. **Radio button label:** Describes the information you want to select or
    unselect.