add copilot-instructions.md file with initial content

Author: firasrg

.github/copilot-instructions.md

@@ -0,0 +1,71 @@
+[//]: # (This file is not a README, it is for GitHub Copilot not for contributors.)
+
+# Copilot Instructions
+
+## Overview
+This project is a [Discord](https://discord.com/) Bot developed in Java, utilizing [JDA (Java Discord API)](https://jda.wiki/introduction/jda/) library for diverse interactions on Together Java server. The project is built with Gradle.
+
+## Project Structure
+
+## Complex Aspects
+
+## Security
+
+## Coding Style
+- Use meaningful variable and method names.
+- Use `@Override` annotation for overridden methods.
+- Use `final` for constants and method parameters that should not be modified.
+- Use `this` keyword to refer to the current instance of a class.
+- No magic numbers or strings; use constants instead.
+- No unnecessary comments; code should be self-explanatory.
+- Use Javadoc for public classes and methods.
+- No wildcard imports; import only the necessary classes.
+- Adhere to the [Google Java Style Guide](https://google.github.io/styleguide/javaguide.html).
+- Use Spotless for code formatting. Run `gradlew spotlessApply` to format code.
+
+## Commands
+1. Create a new class extending `SlashCommandAdapter`.
+2. If the command requires dependencies (e.g., `Database`), accept them in the constructor.
+3. Override methods such as `onSlashCommand`, `onButtonClick`, etc., as needed.
+4. Add the command to the list in `Features.createFeatures`, passing any required dependencies.
+
+Example:
+```java
+public class FooCommand extends SlashCommandAdapter {
+
+    private static final String COMMAND_NAME = "foo";
+
+    private final Database database;
+    private final Config config;
+    
+    public FooCommand(Database database, Config config) {
+        super(COMMAND_NAME, "Foo command using database and config", CommandVisibility.GUILD);
+        this.database = database;
+        this.config = config;
+    }
+
+    @Override
+    public void onSlashCommand(SlashCommandInteractionEvent event) {
+        event.reply("Foo !").queue();
+    }
+}
+```
+
+Commands are registered as features in `org.togetherjava.tjbot.features.Features.createFeatures.java`:
+```java
+public static Collection<Feature> createFeatures(JDA jda, Database database, Config config) {
+    // ... some features
+
+    features.add(new FooCommand(database, config));
+}
+```
+
+## Database
+
+## Error Handling
+
+## Logging
+
+## Testing
+
+## Documentation