I like to browse documentation by index rather than searching.
What you describe is browsing the table of contents.
The Postgres documentation is fairly well organized so this is easy for most topics. However, on the "Chapter 7. Queries" index page, I often think I am in the wrong place if I am looking for information about UNION or ORDER BY, because those keywords are missing from that page. Unlike all the other headings, the headings for these two topics does not include the relevant keywords in teletype. I think it is important to include the keywords, particularly for people whom already know which keyword they're looking for.
The "index" is an actual section and searching for both UNION and ORDER BY turns up entries there.
For example, I propose the following changes: 7.4. Combining Queries -> 7.4. Combining Queries with UNION 7.5. Sorting Rows -> 7.5. Sorting Rows with ORDER BY
Given that 7.6 is named "LIMIT and OFFSET" I don't have an issue with adding the relevant keywords (including EXCEPT and INTERSECT) in those two places.
If there are other examples I've missed where a topic is bound to a specific keyword, they should updated similarly.
