docs: improve JSDoc parameter descriptions for Application constructor

docs/api/context.md

@@ -64,7 +64,7 @@ ctx.state.user = await User.find(id);
 
 ### ctx.app.emit
 
-  Koa applications extend an internal [EventEmitter](https://nodejs.org/dist/latest-v11.x/docs/api/events.html). `ctx.app.emit` emits an event with a type, defined by the first argument. For each event you can hook up "listeners", which is a function that is called when the event is emitted. Consult the [error handling docs](https://koajs.com/#error-handling) for more information.
+  Koa applications extend an internal [EventEmitter](https://nodejs.org/docs/latest/api/events.html). `ctx.app.emit` emits an event with a type, defined by the first argument. For each event you can hook up "listeners", which is a function that is called when the event is emitted. Consult the [error handling docs](https://koajs.com/#error-handling) for more information.
 
 ### ctx.cookies.get(name, [options])
 

docs/api/index.md

@@ -90,10 +90,11 @@ app.listen(3000);
   - `app.env` defaulting to the __NODE_ENV__ or "development"
   - `app.keys` array of signed cookie keys
   - `app.proxy` when true proxy header fields will be trusted
-  - `app.subdomainOffset` offset of `.subdomains` to ignore, default to 2
-  - `app.proxyIpHeader` proxy ip header, default to `X-Forwarded-For`
-  - `app.maxIpsCount` max ips read from proxy ip header, default to 0 (means infinity)
-  - `app.asyncLocalStorage<Boolean|asyncLocalStorage>` - pass `true` or an instance of `AsyncLocalStorage` to enable async local storage. See below for details.
+  - `app.subdomainOffset` offset of `.subdomains` to ignore, defaults to 2
+  - `app.proxyIpHeader` proxy ip header, defaults to `X-Forwarded-For`
+  - `app.maxIpsCount` max ips read from proxy ip header, defaults to 0 (means infinity)
+  - `app.compose` - function to handle middleware composition
+  - `app.asyncLocalStorage` pass `true` or an instance of `AsyncLocalStorage` to enable async local storage. See below for details.
 
   You can pass the settings to the constructor:
   ```js
@@ -232,7 +233,7 @@ function callSomeFunction () {
 }
 ```
 
-Starting in v3.1.0, you can also pass your own AsyncLocalStorage instance:
+Starting in v3.1.0, you can also pass your own `AsyncLocalStorage` instance:
 
 ```js
 const asyncLocalStorage = new AsyncLocalStorage()

lib/application.js

@@ -50,14 +50,14 @@ module.exports = class Application extends Emitter {
   /**
    *
    * @param {object} [options] Application options
-   * @param {string} [options.env='development'] Environment
+   * @param {string} [options.env='development'] Environment. Defaults to `NODE_ENV` or `'development'`.
    * @param {string[]} [options.keys] Signed cookie keys
-   * @param {boolean} [options.proxy] Trust proxy headers
-   * @param {number} [options.subdomainOffset] Subdomain offset
-   * @param {string} [options.proxyIpHeader] Proxy IP header, defaults to X-Forwarded-For
-   * @param {number} [options.maxIpsCount] Max IPs read from proxy IP header, default to 0 (means infinity)
+   * @param {boolean} [options.proxy] When `true`, proxy header fields will be trusted.
+   * @param {number} [options.subdomainOffset] Subdomain offset, defaults to `2`
+   * @param {string} [options.proxyIpHeader] Proxy IP header, defaults to `X-Forwarded-For`
+   * @param {number} [options.maxIpsCount] Max IPs read from proxy IP header, defaults to `0` (means infinity)
    * @param {function} [options.compose] Function to handle middleware composition
-   * @param {boolean} [options.asyncLocalStorage] Enable AsyncLocalStorage, default to false
+   * @param {boolean|AsyncLocalStorage} [options.asyncLocalStorage] Pass `true` or an instance of `AsyncLocalStorage` to enable async local storage.
    *
    */