Changed file uuid variable name in README

All Files in Uploadcare have their Projects, but only UUID is needed to make most of the operations, so this variable mentioning Project ID is counter intuitive

README.md

@@ -211,22 +211,22 @@ Entities are representations of objects in Uploadcare cloud.
 
 #### File
 
-File entity contains its metadata. It also supports `include` param to include additional fields to the file object, such as: "appdata".  
+File entity contains its metadata. It also supports `include` param to include additional fields to the file object, such as: "appdata".
 
 ```ruby
-@file = Uploadcare::File.file("FILE_ID_IN_YOUR_PROJECT", include: "appdata")
+@file = Uploadcare::File.file("FILE_UUID", include: "appdata")
 {
   "datetime_removed"=>nil,
   "datetime_stored"=>"2018-11-26T12:49:10.477888Z",
   "datetime_uploaded"=>"2018-11-26T12:49:09.945335Z",
   "is_image"=>true,
   "is_ready"=>true,
   "mime_type"=>"image/jpeg",
-  "original_file_url"=>"https://ucarecdn.com/FILE_ID_IN_YOUR_PROJECT/pineapple.jpg",
+  "original_file_url"=>"https://ucarecdn.com/FILE_UUID/pineapple.jpg",
   "original_filename"=>"pineapple.jpg",
   "size"=>642,
-  "url"=>"https://api.uploadcare.com/files/FILE_ID_IN_YOUR_PROJECT/",
-  "uuid"=>"FILE_ID_IN_YOUR_PROJECT",
+  "url"=>"https://api.uploadcare.com/files/FILE_UUID/",
+  "uuid"=>"FILE_UUID",
   "variations"=>nil,
   "content_info"=>{
     "mime"=>{
@@ -325,7 +325,7 @@ File entity contains its metadata. It also supports `include` param to include a
 The File object is also can be converted if it is a document or a video file. Imagine, you have a document file:
 
 ```ruby
-@file = Uploadcare::File.file("FILE_ID_IN_YOUR_PROJECT")
+@file = Uploadcare::File.file("FILE_UUID")
 ```
 
 To convert it to an another file, just do:
@@ -440,16 +440,16 @@ As an example, you could store unique file identifier from your system.
 
 ```ruby
 # Get file's metadata keys and values.
-Uploadcare::FileMetadata.index('FILE_ID_IN_YOUR_PROJECT')
+Uploadcare::FileMetadata.index('FILE_UUID')
 
 # Get the value of a single metadata key.
-Uploadcare::FileMetadata.show('FILE_ID_IN_YOUR_PROJECT', 'KEY')
+Uploadcare::FileMetadata.show('FILE_UUID', 'KEY')
 
 # Update the value of a single metadata key. If the key does not exist, it will be created.
-Uploadcare::FileMetadata.update('FILE_ID_IN_YOUR_PROJECT', 'KEY', 'VALUE')
+Uploadcare::FileMetadata.update('FILE_UUID', 'KEY', 'VALUE')
 
 # Delete a file's metadata key.
-Uploadcare::FileMetadata.delete('FILE_ID_IN_YOUR_PROJECT', 'KEY')
+Uploadcare::FileMetadata.delete('FILE_UUID', 'KEY')
 ```
 
 #### Group
@@ -556,7 +556,7 @@ An `Add-On` is an application implemented by Uploadcare that accepts uploaded fi
 
 ```ruby
 # Execute AWS Rekognition Add-On for a given target to detect labels in an image. Note: Detected labels are stored in the file's appdata.
-Uploadcare::Addons.ws_rekognition_detect_labels('FILE_ID_IN_YOUR_PROJECT')
+Uploadcare::Addons.ws_rekognition_detect_labels('FILE_UUID')
 
 # Check the status of AWS Rekognition.
 Uploadcare::Addons.ws_rekognition_detect_labels_status('RETURNED_ID_FROM_WS_REKOGNITION_DETECT_LABELS')
@@ -566,10 +566,10 @@ Uploadcare::Addons.ws_rekognition_detect_labels_status('RETURNED_ID_FROM_WS_REKO
 
 ```ruby
 # ClamAV virus checking Add-On for a given target.
-Uploadcare::Addons.uc_clamav_virus_scan('FILE_ID_IN_YOUR_PROJECT')
+Uploadcare::Addons.uc_clamav_virus_scan('FILE_UUID')
 
 # Checking and purge infected file.
-Uploadcare::Addons.uc_clamav_virus_scan('FILE_ID_IN_YOUR_PROJECT', purge_infected: true )
+Uploadcare::Addons.uc_clamav_virus_scan('FILE_UUID', purge_infected: true )
 
 # Check the status ClamAV virus scan.
 Uploadcare::Addons.uc_clamav_virus_scan_status('RETURNED_ID_FROM_UC_CLAMAV_VIRUS_SCAN')
@@ -579,11 +579,11 @@ Uploadcare::Addons.uc_clamav_virus_scan_status('RETURNED_ID_FROM_UC_CLAMAV_VIRUS
 
 ```ruby
 # Remove background image removal Add-On for a given target.
-Uploadcare::Addons.remove_bg('FILE_ID_IN_YOUR_PROJECT')
+Uploadcare::Addons.remove_bg('FILE_UUID')
 
 # You can pass optional parameters.
 # See the full list of parameters here: https://uploadcare.com/api-refs/rest-api/v0.7.0/#operation/removeBgExecute
-Uploadcare::Addons.remove_bg('FILE_ID_IN_YOUR_PROJECT', crop: true, type_level: '2')
+Uploadcare::Addons.remove_bg('FILE_UUID', crop: true, type_level: '2')
 
 # Check the status of background image removal.
 Uploadcare::Addons.remove_bg_status('RETURNED_ID_FROM_REMOVE_BG')