doc,querystring: use code markup/markdown in headers

Backport-PR-URL: #31108
PR-URL: #31086
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

doc/api/querystring.md

@@ -13,21 +13,21 @@ query strings. It can be accessed using:
 const querystring = require('querystring');
 ```
 
-## querystring.decode()
+## `querystring.decode()`
 <!-- YAML
 added: v0.1.99
 -->
 
 The `querystring.decode()` function is an alias for `querystring.parse()`.
 
-## querystring.encode()
+## `querystring.encode()`
 <!-- YAML
 added: v0.1.99
 -->
 
 The `querystring.encode()` function is an alias for `querystring.stringify()`.
 
-## querystring.escape(str)
+## `querystring.escape(str)`
 <!-- YAML
 added: v0.1.25
 -->
@@ -43,7 +43,7 @@ generally not expected to be used directly. It is exported primarily to allow
 application code to provide a replacement percent-encoding implementation if
 necessary by assigning `querystring.escape` to an alternative function.
 
-## querystring.parse(str\[, sep\[, eq\[, options\]\]\])
+## `querystring.parse(str[, sep[, eq[, options]]])`
 <!-- YAML
 added: v0.1.25
 changes:
@@ -99,7 +99,7 @@ querystring.parse('w=%D6%D0%CE%C4&foo=bar', null, null,
                   { decodeURIComponent: gbkDecodeURIComponent });
 ```
 
-## querystring.stringify(obj\[, sep\[, eq\[, options\]\]\])
+## `querystring.stringify(obj[, sep[, eq[, options]]])`
 <!-- YAML
 added: v0.1.25
 -->
@@ -140,7 +140,7 @@ querystring.stringify({ w: '中文', foo: 'bar' }, null, null,
                       { encodeURIComponent: gbkEncodeURIComponent });
 ```
 
-## querystring.unescape(str)
+## `querystring.unescape(str)`
 <!-- YAML
 added: v0.1.25
 -->