doc,test: add server.timeout property to http2 public API

Both http and https modules have server.timeout property
in public API. This commit adds documentation section and test
for server.timeout in http2 module, so it becomes consistent
with http and https.

Also improves description of callback argument in documentation
for server.setTimeout().

doc/api/http2.md

@@ -1797,9 +1797,28 @@ on the `Http2Server` after `msecs` milliseconds.
 
 The given callback is registered as a listener on the `'timeout'` event.
 
-In case of no callback function were assigned, a new `ERR_INVALID_CALLBACK`
+In case if `callback` is not a function, a new `ERR_INVALID_CALLBACK`
 error will be thrown.
 
+#### `server.timeout`
+<!-- YAML
+added: v8.4.0
+changes:
+ - version: v13.0.0
+ pr-url: https://github.com/nodejs/node/pull/27558
+ description: The default timeout changed from 120s to 0 (no timeout).
+-->
+
+* {number} Timeout in milliseconds. **Default:** 0 (no timeout)
+
+The number of milliseconds of inactivity before a socket is presumed
+to have timed out.
+
+A value of `0` will disable the timeout behavior on incoming connections.
+
+The socket timeout logic is set up on connection, so changing this
+value only affects new connections to the server, not any existing connections.
+
 ### Class: `Http2SecureServer`
 <!-- YAML
 added: v8.4.0
@@ -1943,9 +1962,28 @@ on the `Http2SecureServer` after `msecs` milliseconds.
 
 The given callback is registered as a listener on the `'timeout'` event.
 
-In case of no callback function were assigned, a new `ERR_INVALID_CALLBACK`
+In case if `callback` is not a function, a new `ERR_INVALID_CALLBACK`
 error will be thrown.
 
+#### `server.timeout`
+<!-- YAML
+added: v8.4.0
+changes:
+ - version: v13.0.0
+ pr-url: https://github.com/nodejs/node/pull/27558
+ description: The default timeout changed from 120s to 0 (no timeout).
+-->
+
+* {number} Timeout in milliseconds. **Default:** 0 (no timeout)
+
+The number of milliseconds of inactivity before a socket is presumed
+to have timed out.
+
+A value of `0` will disable the timeout behavior on incoming connections.
+
+The socket timeout logic is set up on connection, so changing this
+value only affects new connections to the server, not any existing connections.
+
 ### `http2.createServer(options[, onRequestHandler])`
 <!-- YAML
 added: v8.4.0

test/parallel/test-http2-server-timeout.js

@@ -3,10 +3,14 @@
 const common = require('../common');
 if (!common.hasCrypto)
  common.skip('missing crypto');
+const assert = require('assert');
 const http2 = require('http2');
 
 const server = http2.createServer();
-server.setTimeout(common.platformTimeout(50));
+server.setTimeout(42000);
+assert.strictEqual(server.timeout, 42000);
+
+server.timeout = common.platformTimeout(50);
 
 const onServerTimeout = common.mustCall((session) => {
  session.close();