Mention drag & drop for non-APK files in help

README.md

@@ -839,6 +839,7 @@ _<kbd>[Super]</kbd> is typically the <kbd>Windows</kbd> or <kbd>Cmd</kbd> key._
  | Enable/disable FPS counter (on stdout)      | <kbd>MOD</kbd>+<kbd>i</kbd>
  | Pinch-to-zoom                               | <kbd>Ctrl</kbd>+_click-and-move_
  | Drag & drop APK file                        | Install APK from computer
+ | Drag & drop non-APK file                    | [Push file to device](#push-file-to-device)
 
 _¹Double-click on black borders to remove them._  
 _²Right-click turns the screen on if it was off, presses BACK otherwise._  

app/scrcpy.1

@@ -364,6 +364,10 @@ Pinch-to-zoom from the center of the screen
 .B Drag & drop APK file
 Install APK from computer
 
+.TP
+.B Drag & drop non-APK file
+Push file to device (see \fB\-\-push\-target\fR)
+
 
 .SH Environment variables
 

app/src/cli.c

@@ -328,6 +328,9 @@ scrcpy_print_usage(const char *arg0) {
         "\n"
         "    Drag & drop APK file\n"
         "        Install APK from computer\n"
+        "\n"
+        "    Drag & drop non-APK file\n"
+        "        Push file to device (see --push-target)\n"
         "\n", arg0);
 }