Allow arbitrary language on code block

[lambdalisue]

It appears that when an unknown language is specified in code blocks, docland fails to generate documentation with the following error:

[uncaught application error]: Error - Unknown language: `vim` is not registered

request: {
  url: "http://0.0.0.0:8080/https://raw.githubusercontent.com/vim-denops/deno-denops-std/main/argument/mod.t"... 1 more character,
  method: "GET",
  hasBody: false
}
response: { status: 500, type: "html", hasBody: true, writable: true }

    at a (https://esm.sh/v91/fault@2.0.1/denonext/fault.mjs:2:312)
    at Object.u [as highlight] (https://esm.sh/v91/lowlight@2.4.1/denonext/lowlight.mjs:2:2820)
    at syntaxHighlight (file:///Users/alisue/ghq/github.com/denoland/docland/components/common.tsx:148:27)
    at MarkdownBlock (file:///Users/alisue/ghq/github.com/denoland/docland/components/markdown.tsx:101:28)
    at renderFunctionalComponent (https://deno.land/x/nano_jsx@v0.0.33/core.ts:160:18)
    at _render (https://deno.land/x/nano_jsx@v0.0.33/core.ts:134:70)
    at https://deno.land/x/nano_jsx@v0.0.33/core.ts:46:17
    at Array.forEach (<anonymous>)
    at appendChildren (https://deno.land/x/nano_jsx@v0.0.33/core.ts:41:12)
    at h (https://deno.land/x/nano_jsx@v0.0.33/core.ts:286:3)
[error] Error: Unknown language: `vim` is not registered

    at a (https://esm.sh/v91/fault@2.0.1/denonext/fault.mjs:2:312)
    at Object.u [as highlight] (https://esm.sh/v91/lowlight@2.4.1/denonext/lowlight.mjs:2:2820)
    at syntaxHighlight (file:///Users/alisue/ghq/github.com/denoland/docland/components/common.tsx:148:27)
    at MarkdownBlock (file:///Users/alisue/ghq/github.com/denoland/docland/components/markdown.tsx:101:28)
    at renderFunctionalComponent (https://deno.land/x/nano_jsx@v0.0.33/core.ts:160:18)
    at _render (https://deno.land/x/nano_jsx@v0.0.33/core.ts:134:70)
    at https://deno.land/x/nano_jsx@v0.0.33/core.ts:46:17
    at Array.forEach (<anonymous>)
    at appendChildren (https://deno.land/x/nano_jsx@v0.0.33/core.ts:41:12)
    at h (https://deno.land/x/nano_jsx@v0.0.33/core.ts:286:3)

I believe docland should allow arbitrary languages in code blocks.

---

[!NOTE]

This causes a "The documentation for this module is currently unavailable." message on the module documentation of deno.land like

It seems this error affects the parent module as well, even though the parent is fine. This is a bit painful for users, as they may feel that the documentation is not ready yet...