docs: add images of led tool, and items sourcing info

README.md

@@ -54,7 +54,9 @@ The PlatformIO Arduino project for the ESP32.  It perfoms the following tasks:
 The list of SpaceAPI endpoints to display is defined in `esp32/src/spacemap.h`.
 The position of an endpoint in the `spaces` array corresponds to the index of the WS2812 LED it controls.
 
-To compile and upload the code to the ESP32, use PlatformIO:
+To compile and upload the code to the ESP32, use [PlatformIO][pio].
+
+Using the PlatformIO Core CLI, upload should be as easy as this single command:
 
 ```shell-session
 pio run -t upload
@@ -67,21 +69,34 @@ A 3D-printable tool that helps with cutting the LED legs to size and attach them
 Usage:
 
 1. Print the tool on a 3D printer.
+
+    ![The 3D printed tool with the LED and connector holes.](images/led_tool_1.jpg)
 2. Put a LED bulb-first into the tool hole.  Especially on first use, make sure that it's all the way in.
+
+    ![Insert the LED.](images/led_tool_2.jpg)
   - The LED should only fit in one orientation.
 3. Use a pair of wire cutters to cut the LED legs as close to the tool's surface as possible.
+
+    ![Cut the LED legs close to the tool's surface.](images/led_tool_3.jpg)
 4. Take a cable fitted with JST ZH-4 connectors and push one connector firmly onto the LED legs inside the tool.
+
+    ![Push the JST ZH-4 connector onto the LED's legs.](images/led_tool_4.jpg)
   - The connector, too, should only (fully) fit in one orientation.
   - You may need to bend the LED legs a little to get them to a pitch close enough to 1.5mm that the connector will slide on.
 5. Pull the cable to remove the connector and LED from the tool.
+
+    ![Pull the assembled piece out of the tool.](images/led_tool_5.jpg)
 6. Repeat steps 2-5 for every LED you need to prepare.
 
+
 ## Components
 
 - WS2812-compatible 5mm bulb LEDs: https://de.aliexpress.com/item/1005005003701575.html
 - Black 5mm LED sockets: https://de.aliexpress.com/item/1005005062684329.html
 - ESP32-C3 Super Mini: https://de.aliexpress.com/item/1005006252882434.html
 - JST-ZH cables: https://de.aliexpress.com/item/1005007298855435.html (4P, Reversed)
+  - I recommend you order a mix of 100mm, 200mm and 300mm cables, as you'll be facing a variety of distances, and having shorter cables available makes for much easier troubleshooting.
+  - In my order, roughly 10% of the cables had a broken wire.  Not sure whether I just got a bad batch, or whether they are just bad quality in general, but I recommend you keep that in mind when ordering.
 
 ## License
 
@@ -99,4 +114,5 @@ If they are not, I license these under the Creative Commons [CC0 1.0][cc0] "No R
 [spaceapi]: https://spaceapi.io
 [erfamap]: https://git.kabelsalat.ch/s3lph/erfamap
 [api.spaceapi.io]: https://api.spaceapi.io/
+[pio]: https://platformio.org/
 [cc0]: https://creativecommons.org/publicdomain/zero/1.0/