migration-to-v2.md

1. Remove the v1 zmk-nodefree-config folder from your zmk-config

2. Add the new Zephyr Module (recommended) or manually copy include/zmk-helpers into zmk-config/config/ (see installation instructions)

3. Fix #include paths:

   1. replace the root-path ../zmk-nodefree-config/ with zmk-helpers/
   2. replace the sub-path keypos_def/ with key-labels/
   3. replace the sub-path international_chars/ with unicode-chars/
   4. rename key-position headers as needed (e.g., keypos_34keys.h becomes 34.h)

   For example:

   // old:
   #include "../zmk-nodefree-config/helper.h"
   #include "../zmk-nodefree-config/keypos_def/keypos_34keys.h"
   #include "../zmk-nodefree-config/international_chars/german.dtsi"
   
   // new:
   #include "zmk-helpers/helper.h"
   #include "zmk-helpers/key-labels/34.h"
   #include "zmk-helpers/unicode-chars/german.dtsi"

4. Change prefix of Danish unicode characters from dk_ to the ISO language code da_

5. Add identifier string to ZMK_CONDITIONAL_LAYER (new syntax)

6. (optional) replace ZMK_BEHAVIOR with explicit behavior helpers