Update docs-search to the latest version, simplify including it in the build

[f-f]

This PR:

• prepares for including 0.0.11 of docs-search
• removes the Template Haskell logic that makes it hard to understand which version is being included in the build, see Updates for v0.14 purescript-docs-search#46 (comment)
• conditionally includes the right version of docs-search depending on the compiler version

[f-f]

cc @cdepillabout: this will probably require adjustments in the nixpkgs build

[cdepillabout]

Thanks for letting me know!