Add new keyboard Tightwriter (#20136)

Co-authored-by: Less/Rikki <86894501+lesshonor@users.noreply.github.com>

keyboards/takashicompany/tightwriter/readme.md

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+# takashicompany/tightwriter
+
+![Tightwriter](https://i.imgur.com/evVMdSRh.jpg)
+
+Tightwriter is a 35-key keyboard.
+The PCB is compatible with Cherry MX compatible key switches and Kailh Choc v1 key switches.
+It can be equipped with backlight LEDs and a TRRS socket.
+
+* Keyboard Maintainer: [takashicompany](https://github.com/takashicompany)
+* Hardware Supported: PCB, Pro Micro
+* Hardware Availability: https://github.com/takashicompany/tightwriter
+
+Make example for this keyboard (after setting up your build environment):
+
+caterina:
+    make takashicompany/tightwriter:default
+
+Many popular Pro Micro alternatives like the Elite-C, Bit-C, Sea-Micro, Puchi-C etc...
+    make takashicompany/tightwriter:default:dfu
+
+See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).
+
+## Bootloader
+
+Enter the bootloader in 3 ways:
+
+- Bootmagic reset: Hold down the top-left key and plug in the keyboard. This will also clear EEPROM, so it is a good first step if the keyboard is misbehaving.
+- Physical reset button: Briefly press the button on the back of the PCB.
+- Keycode in layout: Press the key mapped to QK_BOOT. In the pre-supplied keymaps it is on the ninth layer, replacing the N key.