[skip changelog] Update UPGRADING.md for 0.14.0

Author: silvanocerza

Diff for: docs/UPGRADING.md

@@ -2,4 +2,38 @@
 
 Here you can find a list of migration guides to handle breaking changes between releases of the CLI.
 
-## Unreleased
+## 0.14.0
+
+### Changes in `debug` command
+
+Previously it was required:
+
+- To provide a debug command line recipe in `platform.txt` like `tools.reciped-id.debug.pattern=.....` that will start a
+  `gdb` session for the selected board.
+- To add a `debug.tool` definition in the `boards.txt` to recall that recipe, for example `myboard.debug.tool=recipe-id`
+
+Now:
+
+- Only the configuration needs to be supplied, the `arduino-cli` or the GUI tool will figure out how to call and setup
+  the `gdb` session. An example of configuration is the following:
+
+```
+debug.executable={build.path}/{build.project_name}.elf
+debug.toolchain=gcc
+debug.toolchain.path={runtime.tools.arm-none-eabi-gcc-7-2017q4.path}/bin/
+debug.toolchain.prefix=arm-none-eabi-
+debug.server=openocd
+debug.server.openocd.path={runtime.tools.openocd-0.10.0-arduino7.path}/bin/
+debug.server.openocd.scripts_dir={runtime.tools.openocd-0.10.0-arduino7.path}/share/openocd/scripts/
+debug.server.openocd.script={runtime.platform.path}/variants/{build.variant}/{build.openocdscript}
+```
+
+The `debug.server.XXXX` subkeys are optional and also "free text", this means that the configuration may be extended as
+needed by the specific server. For now only `openocd` is supported. Anyway, if this change works, any other kind of
+server may be fairly easily added.
+
+The `debug.xxx=yyy` definitions above may be supplied and overlayed in the usual ways:
+
+- on `platform.txt`: definition here will be shared through all boards in the platform
+- on `boards.txt` as part of a board definition: they will override the global platform definitions
+- on `programmers.txt`: they will override the boards and global platform definitions if the programmer is selected