Extend upload_flags docs with AVRDUDE example

Resolve #212

Author: valeros

projectconf/section_env_upload.rst

@@ -117,6 +117,22 @@ This option can also be set by global environment variable
 
 Please specify each flag/option in a new line starting with minimum 2 spaces.
 
+Here are a few examples for the ``AVRDUDE`` tool used in Atmel-based platforms:
+
+1.  Enable verbose output and erase chip before uploading
+
+.. code-block:: ini
+
+    [env:atmega4809]
+    platform = atmelmegaavr
+    board = atmega4809
+    framework = arduino
+    upload_flags =
+      -V
+      -e
+
+2.  Configure upload settings and set fuses
+
 .. code-block:: ini
 
     [env:atmega328pb]