vdoc: enable browser custom search with ?q=<search>

[gmlewis]

Some browsers (e.g. Chrome) have a feature called "site search" that allow you to associate a shortcut with a custom site search string URL. For example, the shortcut "gl" can be set to https://pkg.go.dev/search?q=%s such that if you type "gl net/http" the browser would search for https://pkg.go.dev/search?q=net/http which then redirects to https://pkg.go.dev/net/http.

This PR would allow users to create a "vl" shortcut set to https://modules.vlang.io/?q=%s that would immediately act as if the user had typed Ctrl-k followed by their search string.

I have tested this locally with ?q=<alert>yo</alert> and ?q=<alert>yo</alert> and it appears that encodeURIComponent does not need to be called, as these characters are being escaped already.

Note that I ran v test-all locally and there were 5 errors that appear to be unrelated to this change:

---- Summary of `v test-all`: -----------------------------------------------------------------------------------------------
Total runtime: 366120 ms
...
>      Failed: '/Users/glenn/src/github.com/vlang/v/v' -os linux -experimental -b native -o hw.linux examples/hello_world.v
>      Failed: '/Users/glenn/src/github.com/vlang/v/v' -os macos -experimental -b native -o hw.macos examples/hello_world.v
>      Failed: '/Users/glenn/src/github.com/vlang/v/v' -o vtmp_werror -cstrict cmd/v
>      Failed: '/Users/glenn/src/github.com/vlang/v/v' check-md -hide-warnings .
>      Failed: '/Users/glenn/src/github.com/vlang/v/v' -o v.c cmd/v && cc -Werror v.c -lpthread -lm && rm -rf a.out

This was run on a Mac M2 Max running Sonoma 14.2.

[spytheman]

Very slightly related, but can you please share the output of v check-md -hide-warnings . on your system on Discord, or in a new issue here?
I have some working ideas about why v test-all, may be failing the other checks (newer clang compilers can have more strict rules), but I am very puzzled by the v check-md -hide-warnings . failure.