Add more info to README

README.md

@@ -1,4 +1,20 @@
-# Why are there two microcontrollers?
+# About
+
+While setting up some basic home automation, I realized that there things that I'd like to track simply by pressing a button. For example, has anyone fed the dog this morning? She's more than willing to ask for breakfast even if she's already eaten it :)
+
+While searching for a good product for this, I couldn't find one, so I decided to make my own. The primary goals are:
+
+1. It must be cheap, ideally around \$5.
+2. It must be reasonably manufacturable (on the order of 10s to 100s).
+3. It must be re-useable, no tossing it when the battery dies!
+4. It must reasonably small and inoffensive.
+5. It must integrate with HomeAssistant, ideally with minimal configuration.
+
+Unfortunately, shortly after I ordered my first rev of PCBs, Ikea released the $10 [Shortcut Button](https://www.ikea.com/ca/en/p/tradfri-shortcut-button-white-20356382/) which meets most of my criteria. Falling victim to the sunk cost fallacy, I plan to see it through to making a few of these.
+
+# Q&A
+
+## Why are there two microcontrollers?
 
 Cost and ease of development. 
 
@@ -15,17 +31,29 @@ but you might miss the source by the time the ESP wakes up to check the pins.
 Hence, the ATTINY is used to capture the wakeup and inform the ESP8266, who does
 the heavy lifting.
 
-## What about ESP32?
+### What about ESP32?
 
 The cheapest modules I can find at the time of writing are around \$3.50 apiece,
 and they can be power hungry (spikes up to 750mA compared to 400mA, from what I
 read).
 
-## What about ESP32-S2?
+### What about ESP32-S2?
 
 They appear promising and are only \$2 per module on Digikey at the time of
 writing, however they are not supported by platformio yet.
 
-## What about ...?
+### What about ...?
 
 I probably wasn't aware that it exists.
+
+# Development
+
+The standard PlatformIO tooling should work. However, here's a bit of setup I had to do in order to make emacs+clangd happy:
+
+``` sh
+cd <PROJECT_DIR>
+# Create the compile_commands.json
+pio build -t compiledb
+# Link the compile_commmands.json from the git root, which is where tools are expecting it
+ln ./.pio/build/<ENV>/compile_commands.json ../../compile_commands.json
+```