[skip changelog] Remove outdated information re: debug config from platform spec (#1203)

Since the time the documentation for the initial experimental debugging configuration system was added to the Arduino
Platform Specification, the system has changed significantly, resulting in some of the documentation no longer being
applicable to the current version of Arduino CLI. This only removes the outdated information, leaving the parts that are
still correct. The new debug system will be fully documented at a later time.

docs/platform-specification.md

@@ -594,7 +594,6 @@ used for different purposes:
 - **program** a sketch to the target board using an external programmer
 - **erase** the target board's flash memory using an external programmer
 - burn a **bootloader** into the target board using an external programmer
-- **debug** a sketch
 
 Each action has its own recipe and its configuration is done through a set of properties having key starting with
 **tools** prefix followed by the tool ID and the action:
@@ -806,12 +805,9 @@ platform's platform.txt is done as usual.
 Starting from Arduino CLI 0.9.0 / Arduino Pro IDE v0.0.5-alpha.preview, sketch debugging support is available for
 platforms.
 
-The debug action is triggered when the user clicks **Debug > Start Debugging** in the Arduino Pro IDE or runs the
+The debug action is triggered when the user clicks the Debug button in the Arduino Pro IDE or runs the
 [`arduino-cli debug`](commands/arduino-cli_debug.md) command.
 
-The **debug.tool** property specifies the tool ID of the tool to be used for debugging. A **debug.tool** property may be
-defined for each board in boards.txt.
-
 The compiler optimization level that is appropriate for normal usage will often not provide a good experience while
 debugging. For this reason, it may be helpful to use different compiler flags when compiling a sketch for use with the
 debugger. The flags for use when compiling for debugging can be defined via the **compiler.optimization_flags.debug**
@@ -820,13 +816,6 @@ property, and those for normal use via the **compiler.optimization_flags.release
 IDE's **Sketch > Optimize for Debugging** setting or [`arduino-cli compile`](commands/arduino-cli_compile.md)'s
 `--optimize-for-debug` option.
 
-The debug recipe is defined via **tools.TOOL_NAME.debug.pattern**. It can be built concatenating the following
-automatically generated properties:
-
-- `{interpreter}`: the GDB command interpreter to use. It is configurable via
-  [`arduino-cli debug --interpreter`](commands/arduino-cli_debug.md). This property was added in Arduino CLI 0.10.0 /
-  Arduino Pro IDE v0.0.7-alpha.preview.
-
 ## Custom board options
 
 It can sometimes be useful to provide user selectable configuration options for a specific board. For example, a board