Add Configuration section to readme

README.md

@@ -130,10 +130,43 @@ Press the button to display the next set of Braille patterns.
 
 ## Configuration
 
+You can configure the project to your liking:
+
+Setting                 | Category  | Type | Default   | Notes
+----------------------: |---------- | ---- | --------- | :----
+`AUTO_PIN`              | **`PIN`** | uint | `7`       | 74HC595 shift register - pin `Q7`<br>_alternatively, can be pin_ `Q6`
+`BUTTON_PIN`            | **`PIN`** | uint | `8`       | -
+`DATA_PIN`              | **`PIN`** | uint | `11`      | 74HC595 shift register - pin `DS`
+`LATCH_PIN`             | **`PIN`** | uint | `12`      | 74HC595 shift register - pin `ST_CP`
+`CLOCK_PIN`             | **`PIN`** | uint | `13`      | 74HC595 shift register - pin `SH_CP`
+`BAUD_RATE`             | **`SRL`** | uint | `9600`    | Serial speed
+`SERIAL_ECHO`           | **`SRL`** | bool | `true`    | if symbols must be printed to Serial as they are being sent to Braille display
+`LF_IS_EOM`             | **`SRL`** | bool | `true`    | Linefeed is EOM<br>_if false, messages before and after LF symbol are concatinated_
+`SERIAL_NA_IS_EOM`      | **`SRL`** | bool | `false`   | Serial Not Available is EOM<br>_if false, messages before and after Serial not available are concatinated_
+`BUTTON_CLICK_MS`       | **`BTN`** | uint | `100`     | min delay between consecutive clicks to prevent jitter _(in ms)_
+`BUTTON_CYCLE_MS`       | **`BTN`** | uint | `1000`    | delay between autoclicks while button is kept pressed _(in ms)_
+`AUTOCOUNT_CELLS`       | **`CEL`** | bool | `true`    | if Braille cells must be automatically counted
+`BRAILLE_CELLS`         | **`CEL`** | uint | `4`       | number of Braille cells if they are not automatically counted
+`ANIMATION_ON_START`    | **`ANM`** | bool | `true`    | if to play animation on start
+`ANIMATION_MS_PER_CELL` | **`ANM`** | uint | `500`     | delay between each animation frame _(in ms)_
+
+Configurations priority (from highest to lowest):
+1. **`platformio.ini`**
+    - works only if using `PlatformIO`
+    - add required `-D <setting>=<value>` lines to `build_flags` section
+    - if you want to change `BAUD_RATE`, consider editing `monitor_speed` instead
+    _<br>(`BAUD_RATE` will be set automatically, ensuring Serial monitor speed is synchronized with it)_
+2. **`src/custom_config.h`**
+    - **THE PREFERRED WAY**
+    - uncomment neccessary defines and set their values
+    - keep in mind that settings from **`platformio.ini`** can override settings defined here
+3. **`src/config.h`**
+    - **PLEASE DO NOT EDIT THIS FILE**
+    - contains default setting values
+
 
 ## Todo
 
-- Add Customization section to README
 - Add Russian variant of README
 - Add tests
 - Optimize `nchar**_t` type for symbols with translation to Braille