Additional phrasing fixes; add layer numbers; fix order

Author: CVYY39

docs/getting-started.md

@@ -1,12 +1,12 @@
 # Get started with M60 Keyboard
 
-M60 is a compact keyboard. It has a keymap composed of multiple layers, which is [similar to TMK Keyboard](https://github.com/tmk/tmk_keyboard/blob/master/tmk_core/doc/keymap.md). By default, No.0 layer is used:
+M60 is a compact keyboard. It has a keymap composed of multiple layers, [similar to TMK Keyboard](https://github.com/tmk/tmk_keyboard/blob/master/tmk_core/doc/keymap.md). By default, layer number 0 is used, which includes a normal key map:
 
 ![](https://gitee.com/makerdiary/python-keyboard/raw/resource/img/layer0.svg)
 
 ## Keymap
 
-As the 60% keyboard lacks a lot of keys such as F1~F12 and arrow keys, <kbd>Fn</kbd> is used to activate a new layer.
+As the 60% keyboard lacks a lot of keys such as F1~F12 and arrow keys, <kbd>Fn</kbd> is used to activate a second layer, layer number 1.
 
 By default, holding <kbd>Fn</kbd> down activates the following functions:
 
@@ -20,17 +20,9 @@ Except for <kbd>Fn</kbd>, any normal key can be used as a Tap-key. A Tap-key is
 
 All of the default Tap-keys, including <kbd>D</kbd>, <kbd>B</kbd>, and <kbd>;</kbd> can be [re-configured](configuration.md).
 
-### Using <kbd>B</kbd> to configure Bluetooth and USB
-
-<kbd>B</kbd> is the default Tap-key to configure Bluetooth and USB. Tapping <kbd>B</kbd> (i.e., pressing & releasing it quickly) outputs `b`. Holding <kbd>B</kbd> down activates another the Bluetooth keyboard layer. When the Bluetooth layer is active, the following functions are available:
-
-- <kbd>B</kbd> + <kbd>Esc</kbd> toggles Bluetooth
-- <kbd>B</kbd> + <kbd>0</kbd> ~ <kbd>9</kbd> changes Bluetooth ID to switch between multiple computers and phones
-- <kbd>B</kbd> + <kbd>U</kbd> toggles USB
-
 ### Using <kbd>D</kbd> for Navigation
 
-<kbd>D</kbd> is the default Tap-key to activate the navigation functions.
+<kbd>D</kbd> is the default Tap-key to activate the navigation functions. Holding it activates layer number 2, which includes navigation keys:
 
 ![](https://gitee.com/makerdiary/python-keyboard/raw/master/img/d-for-navigation.png)
 
@@ -41,6 +33,14 @@ All of the default Tap-keys, including <kbd>D</kbd>, <kbd>B</kbd>, and <kbd>;</k
 - <kbd>D</kbd> + <kbd>U</kbd> → <kbd>PgUp</kbd>
 - <kbd>D</kbd> + <kbd>N</kbd> → <kbd>PgDn</kbd>
 
+### Using <kbd>B</kbd> to Configure Bluetooth and USB
+
+<kbd>B</kbd> is the default Tap-key to configure Bluetooth and USB. Tapping <kbd>B</kbd> (i.e., pressing & releasing it quickly) outputs `b`. Holding <kbd>B</kbd> down activates another the Bluetooth keyboard layer, layer number 3. When the Bluetooth layer is active, the following functions are available:
+
+- <kbd>B</kbd> + <kbd>Esc</kbd> toggles Bluetooth
+- <kbd>B</kbd> + <kbd>0</kbd> ~ <kbd>9</kbd> changes Bluetooth ID to switch between multiple computers and phones
+- <kbd>B</kbd> + <kbd>U</kbd> toggles USB
+
 ### Using <kbd>;</kbd> as <kbd>Ctrl</kbd>
 
 <kbd>;</kbd> is a different type of Tap-key. Tapping <kbd>;</kbd> outputs `;`. However, holding <kbd>;</kbd> down outputs `Ctrl` instead of activating a layer.
@@ -56,9 +56,9 @@ All of the default Tap-keys, including <kbd>D</kbd>, <kbd>B</kbd>, and <kbd>;</k
 
 Simultaneously pressing two keys (i.e., pressing them in an interval of less than 10ms) activates an alternate function.
 
-Two sets of pair-keys are configured by default, to illustrate how to set up these keys. These include <kbd>J</kbd> <kbd>K</kbd> and <kbd>U</kbd> <kbd>I</kbd>. As shipped, simultaneously pressing <kbd>J</kbd> and <kbd>K</kbd> or <kbd>U</kbd> and <kbd>I</kbd> in a text editor will output a pre-defined string (_e.g._, "You just triggered pair keys #0").
+Two sets of pair-keys are configured by default, to illustrate how to setup these keys. These include <kbd>J</kbd> <kbd>K</kbd> and <kbd>U</kbd> <kbd>I</kbd>. As shipped, simultaneously pressing <kbd>J</kbd> and <kbd>K</kbd> or <kbd>U</kbd> and <kbd>I</kbd> in a text editor will output a pre-defined string (_e.g._, "You just triggered pair keys #0").
 
-## Setup Bluetooth
+## How to Setup Bluetooth
 
 First, press <kbd>B</kbd> + <kbd>1</kbd> to start Bluetooth advertising. You will then see the blue LED under <kbd>1</kbd> enter in "breathing" mode and flash slowly：
 
@@ -78,8 +78,8 @@ Choose `Bluetooth` in the `Add a device` dialog, then you will see the device `P
 
 In order to connect the keyboard to a second computer, just use <kbd>B</kbd> + <kbd>2</kbd> to start connecting. From <kbd>0</kbd> to <kbd>9</kbd>, the keyboard can connect to 10 bluetooth devices.
 
-## Go further
+## Go Further
 
 We hope M60 keyboard incites ideas to make a keyboard more productive, all without having to install any third-party software or drivers on your computer.
 
-If you have your own thoughts on how to best configure the keyboard, just follow [the configuring guide](configuration.md) to find what works best for you.
+If you have your own thoughts on how to best configure the keyboard, just follow [the configuration guide](configuration.md) to find what works best for you.