feat: add javascript code block support (#13)

docs/README.md

@@ -211,7 +211,7 @@ _(Note: `httpbin.org/post` wraps the JSON sent in a "json" field in its response
 GET https://httpbin.org/status/201
 ```
 
-The request to `/status/201` completed with status code: **{{{{response.status}}}}**.
+The request to `/status/201` completed with status code: **{{{response.status}}}**.
 ````
 
 ## Managing Documents
@@ -259,8 +259,8 @@ http.md build mydoc.md output.md -i baseUrl=https://api.production.example.com -
 
 ````markdown
 ```http
-GET {{{{input.baseUrl}}}}/users/1
+GET {{{input.baseUrl}}}/users/1
-Authorization: Bearer {{{{input.apiKey}}}}
+Authorization: Bearer {{{input.apiKey}}}
 ```
 
 ::response
@@ -336,8 +336,8 @@ You can configure the behavior of each `http` code block by adding options to it
 
 ````markdown
 ```http id=complexRequest,json,yaml,hidden
-POST {{{{input.apiEndpoint}}}}/data
+POST {{{input.apiEndpoint}}}/data
-X-API-Key: {{{{input.apiKey}}}}
+X-API-Key: {{{input.apiKey}}}
 Content-Type: application/json
 
 # Request body written in YAML, will be converted to JSON