hot-reload: Add docs for hot-reload

SUMMARY.md

@@ -67,6 +67,7 @@
 * [Memory Management](administration/memory-management.md)
 * [Monitoring](administration/monitoring.md)
 * [HTTP Proxy](administration/http-proxy.md)
+* [Hot Reload](administration/hot-reload.md)
 * [Troubleshooting](administration/troubleshooting.md)
 
 ## Local Testing

administration/hot-reload.md

@@ -0,0 +1,50 @@
+---
+description: Enable hot reload through a command line argument or a HTTP endpoint
+---
+
+# Hot Reload
+
+FLuent Bit supports hot relaoding feature when enabling via command line with `-Y` or `--enable-hot-reload` option.
+
+## Getting Started
+
+To get started, the first step is to enable the HTTP Server from the configuration file:
+
+```
+[SERVICE]
+    HTTP_Server  On
+    HTTP_Listen  0.0.0.0
+    HTTP_PORT    2020
+
+# Other stuffs of plugin configurations
+```
+
+The above configuration snippet will enable HTTP endpoint for hot reloading.
+
+## How to reload
+
+### via HTTP
+
+Hot reloading can be kicked via HTTP endpoints that are:
+
+* `PUT /api/v2/reload`
+* `POST /api/v2/reload`
+
+If users don't enable hot reloading feature, hot reloading via these endpoinds does not work.
+
+For using curl to reload fluent-bit, users must specify empty request body as:
+
+
+```text
+$ curl -XPOST -d {} localhost:2020/api/v2/reload
+```
+
+### via Signal
+
+Hot reloading also can be kicked via `SIGHUP`.
+
+`SIGHUP` signal is not supported on Windows. So, users can't enable this feature on Windows.
+
+## Limitations
+
+Hot reloading feature is currently working on Linux and macOS. And Windows is not supported yet.