Documentation: add migration guide to the USB documentation (#16)

Documentation/Doxygen/USB/USB.dxy.in

@@ -927,6 +927,7 @@ INPUT                  = src/usb.txt \
                          src/usb_classes.txt \
                          src/usb_function_reference.txt \
                          src/usb_resource_requirements.txt \
+                         src/usb_migration.txt \
                          src/Reference_Files.txt \
                          src/usb_structs.txt \
                          src/rl_usb.txt \

Documentation/Doxygen/USB/src/usb.txt

@@ -30,6 +30,7 @@ This user's guide contains the following chapters:
 - \ref USB_Classes provides details about the supported USB Device Classes.
 - \ref usb_function_reference lists the complete API of the USB Component.
 - \ref usb_resource_requirements shows the configuration of system resources for USB Component in detail.
+- \ref usb_migration contains information how to migrate projects to latest version of USB Component (v8).
 - [**API Reference**](./modules.html) shows the directory and file organization and contains the detailed API description.
 
 The <a class="el" href="https://www.usb.org/developers" target="_blank">USB-IF Developers Area</a> contains the complete

Documentation/Doxygen/USB/src/usb_migration.txt

@@ -0,0 +1,68 @@
+/*=======0=========1=========2=========3=========4=========5=========6=========7=========8=========9=========0=========1====*/
+/**
+\page usb_migration Migration Guide
+
+<b>MDK-Middleware v8</b> introduced the following changes:
+
+  - <b>General</b>:
+    - <b>MDK bundle</b> with source code replaces MDK-Pro and MDK-Plus bundles with pre-built libraries.
+    - <b>removed CORE component variants</b>.
+    - added requirement for C compiler version 11 (C11).
+    - removed support for legacy Arm Compiler 5.
+    - removed support for CMSIS-RTOS version 1.
+
+  - <b>USB debug</b>:
+    - <b>changed source configuration file to header</b> (USB_Debug.c -> USB_Debug.h).
+
+  - <b>USB Device specific</b>:
+    - <b>changed source configuration files to headers</b> (USBD_Config_0..3.c -> USBD_Config_0..3.h).
+
+  - <b>USB Host specific</b>:
+    - <b>changed source configuration files to headers</b> (USBH_Config_0..3.c -> USBH_Config_0..3.h).
+    - <b>removed OHCI and EHCI drivers (moved to CMSIS-Driver pack)</b>.
+
+The following sections show how to migrate projects from previous version of the MDK-Middleware (v7):
+  - \ref usb_migration_component describes how to migrate the USB Component selection.
+  - \ref usb_migration_config describes how to migrate the USB Component configuration.
+
+\section usb_migration_component Component migration
+
+To migrate the USB Component make the following changes to component selection:
+  - <b>Keil::USB</b>: select <b>MDK</b> bundle instead MDK-Pro or MDK-Plus bundle.
+  - <b>Keil::USB:CORE</b>: deselect <b>Debug</b> or <b>Release</b> variant if one was selected.
+
+\note If the <b>Event Recorder</b> was used for debugging, please select the <b>Event Recorder</b>
+      from the <b>CMSIS-View</b> pack instead the one from the <b>ARM_Compiler</b> pack.
+
+\note USB Component requires C Compiler supporting C11 standard or higher
+
+If any other component is used, like Network or File System, please refer to its Migration Guide.
+
+\section usb_migration_config Configuration migration
+
+Debug:
+  - if the <b>USB_Debug.c</b> file exists, then compare it with the new <b>USB_Debug.h</b> file and copy
+    old values into the new file:
+    - if the old file does not exist then debugging was not configured previously
+    - note that <b>USB Device Debug</b> and <b>USB Host Debug</b> order has swapped in the new configuration file.
+    - \image html usb_debug_migrate.png "Old USB_Debug.c to new USB_Debug.h" width=90%
+
+USB Device:
+  - compare the existing <b>USBD_Config_0..3.c</b> files with the new <b>USBD_Config_0..3.h</b> files and copy
+    old values into the new files:
+    - \image html usbd_config_migrate.png "Old USBD_Config_0..3.c to new USBD_Config_0..3.h" width=90%
+
+USB Host:
+  - compare the existing <b>USBH_Config_0..3.c</b> files with the new <b>USBH_Config_0..3.h</b> files and copy
+    old values into the new files:
+    - the <b>USBH_Config_0..3.h</b> does not contain separate settings for <b>Custom</b>, <b>OHCI</b> or <b>EHCI</b>
+      controllers anymore, so to migrate to the new configuration file note which <b>Controller Interface</b>
+      was selected in the old <b>USBH_Config_0..3.c</b> file and copy appropriate controller's previous settings
+      to the new configuration file.
+    - for <b>Memory Pool Size</b> update the new value by <b>adding 128</b> since old setting did not include
+      additional necessary space for memory pool internal operation.
+    - \image html usbh_config_migrate.png "Old USBD_Config_0..3.c to new USBD_Config_0..3.h" width=90%
+
+\note <b>OHCI</b> and <b>EHCI</b> drivers are not a part of the <b>MDK-Middleware</b> anymore but are distributed separately
+      via the <b>CMSIS-Driver</b> pack, so please consult CMSIS-Driver documentation on configuring and using those drivers.
+*/