[InstagramBridge] Documentation for configuring this bridge (#2437)

README.md

@@ -22,7 +22,7 @@ Supported sites/pages (examples)
 * `FlickrExplore` : [Latest interesting images](http://www.flickr.com/explore) from Flickr
 * `GoogleSearch` : Most recent results from Google Search
 * `Identi.ca` : Identica user timeline (Should be compatible with other Pump.io instances)
-* `Instagram`: Most recent photos from an Instagram user (There is an [issue](https://github.com/RSS-Bridge/rss-bridge/issues/1891) for public instances)
+* `Instagram`: Most recent photos from an Instagram user (It is recommended to [configure](doc/bridges/InstagramBridge.rst) this bridge to work)
 * `OpenClassrooms`: Lastest tutorials from [fr.openclassrooms.com](http://fr.openclassrooms.com/)
 * `Pinterest`: Most recent photos from user or search
 * `ScmbBridge`: Newest stories from [secouchermoinsbete.fr](http://secouchermoinsbete.fr/)

doc/bridges/InstagramBridge.rst

@@ -0,0 +1,46 @@
+=================
+ InstagramBridge
+=================
+
+To somehow bypass the `rate limiting issue <https://github.com/RSS-Bridge/rss-bridge/issues/1891>`_,
+it is suggested to deploy a private RSS-Bridge instance that uses a working Instagram account.
+
+Configuration
+-------------
+
+1. Retreiving session id.
+The following steps describe how to get the session id using a Chromium-based browser.
+
+- Create an Instagram account, that you will use for your RSS-Bridge instance.
+It is NOT recommended to use your existing account that is used for common interaction with Instagram services.
+
+- Login to Instagram
+
+- Open DevTools by pressing F12
+
+- Open "Networks tab"
+
+- In the "Filter" field input "i.instagram.com"
+
+- Click on "Fetch/XHR"
+
+- Refresh web page
+
+- Click on any item from the table of http requests
+
+- In the new frame open the "Headers" tab and scroll to "Request Headers"
+
+- There will be a cookie param will lots of ``<key>=<value>;`` text. You need the value of the "sessionid" key. Copy it.
+
+2. Configuring RSS-Bridge
+
+- In config.ini.php add following configuration:
+
+.. code-block::
+
+   [InstagramBridge]
+   session_id = %sessionid from step 1%
+   cache_timeout = %cache timeout in seconds%
+
+The bigger the cache_timeout value, the smaller the chance for RSS-Bridge to throw 429 errors.
+Default cache_timeout is 3600 seconds (1 hour).