Revise the Installation part of the Tera Term section of the Serial docs page. (#6675)

* Revise Tera Term installation page

* Update serial.md

adjust release page info somewhat

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Co-authored-by: Galen Nickel <gnickel@aquent.com>

Author: DotLYHiyou

docs/device/serial.md

@@ -35,7 +35,7 @@ Also, if you don't see the serial port as one of your computer's devices, you mi
 
 ### Windows > Tera Term
 
-* Install the terminal emulator [Tera Term](https://ttssh2.osdn.jp/index.html.en). At the time of this writing, the latest version is 4.88 and can be downloaded [from here](http://en.osdn.jp/frs/redir.php?m=jaist&f=%2Fttssh2%2F63767%2Fteraterm-4.88.exe). Follow the instructions from the installer.
+* Install the terminal emulator [Tera Term](https://teratermproject.github.io/index-en.html). The the latest release and can be downloaded [from here](https://github.com/TeraTermProject/teraterm/releases). Scroll down to the "Assets" section and download the release package that is appropriate for your computer. For example, if you have an x64 based processor, click on the one that ends in "x64.exe".
 
 Once both the driver and the terminal emulator are installed, plug in the micro:bit and wait until the device is fully setup. Then, open TeraTerm.