docs: add description for q query parameter

[ChrisCho-H]

added guideline description for query parameter q, so that dev would not be confused.

[fiatjaf]

This is not correct, and got me confused.

[ChrisCho-H]

As I understand, In a situation where A wallet tries to withdraw to B wallet using lnurl is like

1. A wallet gives encoded lnurl like lnurl1...
2. B wallet decodes it(which would be https...?q=abc...) and request get info
3. A wallet use query param q to identify the request and return identified withdrawal request info like

   {
   "tag": "withdrawRequest", // type of LNURL
   "callback": string, // The URL which LN SERVICE would accept a withdrawal Lightning invoice as query parameter
   "k1": string, // Random or non-random string to identify the user's LN WALLET when using the callback URL
   "defaultDescription": string, // A default withdrawal invoice description
   "minWithdrawable": number, // Min amount (in millisatoshis) the user can withdraw from LN SERVICE, or 0
   "maxWithdrawable": number, // Max amount (in millisatoshis) the user can withdraw from LN SERVICE, or equal to minWithdrawable if the user has no choice over the amounts
   }

   and in this step, k1 value is actually same with q query parameter.

and also same with k1 used in callback in next step

<callback>
  <?|&> // either '?' or '&' depending on whether there is a query string already in the callback
   k1=<k1> // the k1 specified in the response above
  &pr=<lightning invoice> // the payment request generated by the wallet

@fiatjaf in what point is not correct? I'm just wondering.

[fiatjaf]

There is no q parameter anywhere, this is not specified. You can use a q parameter if you want, but this is your choice, shouldn't be in the spec. You can use any parameters you desire.

[ChrisCho-H]

alright. thx!