fix(tools): get docstrings from module file

[aspeddro]

FROM_COMPILER=true ./analysis/rescript-editor-analysis.exe extractDocs ~/Desktop/projects/rescript-compiler/jscomp/others/belt.res | jq '{items}[] | map(select(.id == "Belt.Array")) | .[0] | .docstrings'

Before:

[
  "[`Belt.Array`]()\n\n  **mutable array**: Utilities functions"
]

After:

[
  "Utililites for `Array` functions.\n\n### Note about index syntax\n\nCode like `arr[0]` does *not* compile to JavaScript `arr[0]`. Reason transforms\nthe `[]` index synta
x into a function: `Array.get(arr, 0)`. By default, this\nuses the default standard library's `Array.get` function, which may raise an\nexception if the index isn't found. 
If you `open Belt`, it will use the\n`Belt.Array.get` function which returns options instead of raising exceptions. \n[See this for more information](../belt.mdx#array-acce
ss-runtime-safety)."
]

[zth]

Should we get both rather than dropping one of them?

[aspeddro]

of course, it's an array