Add a modal form like this to your site with SearchWP’s Modal Search Form Extension!
View the installation guide, browse the Knowledge Base, find out about SearchWP’s many hooks
Search results will be limited to Documentation thanks to a SearchWP Supplemental Engine
Customize the order of search results for particular queries, ensuring that certain entries appear first!
If you’re not comfortable (or able) to edit template files to implement search forms and results, this extension provides Shortcodes that generate both search forms and results loops for SearchWP search engines