Update readme

Author: sentosango

README.md

@@ -27,7 +27,69 @@ foreach ($response->json() as $device) {
 }
 ```
 
-TODO: Add more usage instructions for other endpoints...
+## List of available API methods
+
+- System
+  - Get list of directories
+  - Get devices info
+  - Get|Update debug facilities
+  - Get local discovery cache
+  - Get|Create|Delete recent errors
+  - Get paths
+  - Pause|Resume syncing
+  - Ping
+  - Erase index
+  - Get system version|status|log
+  - Check upgrade possibility
+  - Upgrade
+  - Restart|Shutdown
+- Config
+  - Get|Update full config
+  - Check if restart is required
+  - Get all folders (or devices)
+  - Create|Get|Update|Delete folder or device
+  - Get|Replace default folder (or device) configuration
+  - Get|Replace default ignore patterns
+  - Get|Update config options
+  - Get|Update ldap config
+  - Get|Update gui config
+- Cluster
+  - List|Remove records about remote pending folder (or device)
+- Folder
+  - Get folder errors
+  - Get|Restore files versions
+- Database
+  - Get directory tree
+  - Get completion percentage
+  - Get file info
+  - Get|Update folder ignores
+  - Get local changed files
+  - Get needed files
+  - Override remote folder
+  - Force file download priority
+  - Get remote needed files
+  - Revert local changes
+  - Rescan
+  - Get folder status
+- Events
+  - Get events
+  - Get disk events
+- Statistics
+  - Get devices|folders statistics
+- Misc
+  - Get formatted device ID
+  - Get canonical language code
+  - Get random string
+  - Get usage report data
+- Debug
+  - Get completion summary
+  - Get http metrics
+  - Get CPU profile
+  - Get heap memory profile
+  - Collect debug info
+  - Get debug info about file
+- No auth
+  - Get health status
 
 ## License