add usage to readme

Author: JulianVennen

README.md

@@ -5,6 +5,73 @@ A java library used to list and share log files to the [mclo.gs](https://mclo.gs
 - Remove IPv4 and IPv6 addresses before uploading the log
 - Trim logs and shorten them to 10 MB before uploading
 
+### Usage
+This project is available from Maven Central, so you just need to add the dependency to your project:
+
+#### Gradle
+```gradle
+dependencies {
+    implementation 'gs.mclo:api:3.0.0'
+}
+```
+
+#### Maven
+```xml
+<dependency>
+  <groupId>gs.mclo</groupId>
+  <artifactId>api</artifactId>
+  <version>3.0.0</version>
+</dependency>
+```
+
+### Upload a log file
+
+Obtaining a log file:
+```java
+// by path
+var log = new Log(Paths.get("./logs/latest.log"));
+// or by raw content
+log = new Log("example content");
+```
+
+Creating a client:
+```java
+// Create a client with a project name and version
+var client = new MclogsClient("mclogs-java-example", "1.0.0");
+// optionally with a minecraft version
+client = new MclogsClient("mclogs-java-example", "1.0.0", "1.12.2");
+// or with a custom user agent
+client = new MclogsClient("mclogs-java-example/1.0.0");
+```
+
+Sharing the log file:
+```java
+// share the log file
+var apiResponse = client.uploadLog(log);
+System.out.println(apiResponse.getUrl());
+```
+
+There are also shortcuts for posting raw content or a path:
+```java
+// share a log file by path
+var apiResponse = client.uploadLog(Paths.get("./logs/latest.log"));
+// share a log file by raw content
+apiResponse = client.uploadLog("example content");
+```
+
+### Fetch a log file's contents
+```java
+String secondResponse = client.getRawLogContent("HpAwPry");
+```
+
+### Using a self-hosted instance of mclogs
+```java
+Instance instance = new Instance();
+instance.setApiBaseUrl("https://api.logs.example.com");
+instance.setViewLogUrl("https://api.logs.example.com");
+client.setInstance(instance);
+```
+
 This library is used in the mclogs plugin and mods:
 [Bukkit](https://github.com/aternosorg/mclogs-bukkit) |
 [Forge](https://github.com/aternosorg/mclogs-forge) |