Added docs for custom attachments

Author: martinmitrevski

DemoAppSwiftUI/CustomComposerAttachmentView.swift

@@ -18,8 +18,6 @@ struct ContactAttachmentPayload: AttachmentPayload {
     let phoneNumber: String
 }
 
-typealias ContactAttachment = ChatMessageAttachment<ContactAttachmentPayload>
-
 extension ContactAttachmentPayload: Identifiable {
 
     var id: String {
@@ -53,7 +51,6 @@ class CustomAttachmentsFactory: ViewFactory {
             id: "127",
             content: AnyAttachmentPayload(payload: ContactAttachmentPayload(name: "Test 5", phoneNumber: "534534543543534"))
         )
-        
     ]
 
     func makeAttachmentSourcePickerView(
@@ -203,7 +200,7 @@ struct CustomContactAttachmentView: View {
                     .frame(maxWidth: .infinity)
                 }
             }
-        }        
+        }
     }
 
 }

Sources/StreamChatSwiftUI/ChatChannel/Composer/AttachmentPickerTypeView.swift

@@ -20,6 +20,8 @@ public enum AttachmentPickerType {
     case media
     /// Giphy commands are selected.
     case giphy
+    /// Custom attachment picker type.
+    case custom
 }
 
 /// View for picking the attachment type (media or giphy commands).