Merge pull request #4556 from amyreinholds/patch-2

Style Guide updates: fixed broken link, added info

src/content/docs/style-guide/writing-guidelines/levels-headings.mdx

@@ -11,9 +11,9 @@ redirects:
   - /docs/new-relic-only/advanced-style-guide/writing-guidelines/levels-headings
 ---
 
-Taking some time to consider your headings and document titles will be time well spent. Titles and headings are not only important for search results, but they can make your docs easier to skim.
+Taking some time to consider your headings and document titles is time well spent. Titles and headings are not only important for search results, but they can make your docs easier to skim.
 
-For all headings and document titles, use [sentence case](/docs/style-guide/writing-guidelines/capitalization#heading_caps).
+For all headings, subheadings, and titles use [sentence case](/docs/style-guide/quick-reference/capitalization#heading_caps). This means you should capitalize the first word of the title and proper nouns only. You should also capitalize the first word after a colon. Avoid dashes and ellipses in headlines and titles. Avoid using punctuation, with the exception of question marks.
 
 ## Use parallel construction [#parallel]