Improve README

README.md

@@ -32,6 +32,7 @@ If you don't want any "spoiler text", just leave the line empty.
 | limit               | Limit send per minute per person                                                                                            | int                    |
 | limit_hour          | Limit send par hour per person                                                                                              | int                    |
 | collection_url      | URL of website you deserve image. `<collection>` is a variable who depend on collection.json (you can remove this variable) | string                 |
+| unsplash_client_id  | Access key of your Unsplash App (you can create it on api.unsplash.com )                                                    | string                 |
 
 Copy `blacklist.sample.json` to `blacklist.json` and replace or add accounts that should not receive any image
 

config.sample.txt

@@ -10,3 +10,4 @@ spoiler_text: some text here
 limit: 2
 limit_hour: 10
 collection_url: https://source.unsplash.com/collection/<collection>/
+unsplash_client_id: "03ad5bfbaa0acd6c96a728d425e533683ec25e5fb7fcf99f6461720b3d0d75a1"