[Docs] update git command and directory name of documents (qmk#7619)

Author: umi-umi

docs/getting_started_github.md

@@ -19,7 +19,7 @@ And be sure to select "HTTPS", and select the link and copy it:
 From here, enter `git clone ` into the command line, and then paste your link:
 
 ```
-user@computer:~$ git clone https://github.com/whoeveryouare/qmk_firmware.git
+user@computer:~$ git clone --recurse-submodules https://github.com/whoeveryouare/qmk_firmware.git
 Cloning into 'qmk_firmware'...
 remote: Counting objects: 46625, done.
 remote: Compressing objects: 100% (2/2), done.

docs/getting_started_introduction.md

@@ -4,7 +4,7 @@ This page attempts to explain the basic information you need to know to work wit
 
 ## Basic QMK Structure
 
-QMK is a fork of [Jun Wako](https://github.com/tmk)'s [tmk_keyboard](https://github.com/tmk/tmk_keyboard) project. The original TMK code, with modifications, can be found in the `tmk` folder. The QMK additions to the project may be found in the `quantum` folder. Keyboard projects may be found in the `handwired` and `keyboard` folders.
+QMK is a fork of [Jun Wako](https://github.com/tmk)'s [tmk_keyboard](https://github.com/tmk/tmk_keyboard) project. The original TMK code, with modifications, can be found in the `tmk_core` folder. The QMK additions to the project may be found in the `quantum` folder. Keyboard projects may be found in the `handwired` and `keyboard` folders.
 
 ### Userspace Structure