doc: add the explanation on how to read/write strategy fields

doc/topics/rw-strategy.md

@@ -0,0 +1,56 @@
+## Print/Modify Strategy Fields
+
+The following utility functions are commonly used in the `elliottwave` and `drift` strategies. You can refer to their implementations in `pkg/strategy` for further details.
+
+To handle output or modification of strategy fields, BBGO offers a utility that simplifies parameter serialization, similar to how JSON fields are marshaled. This utility adopts JSON-like tag syntax with additional tags for specific behaviors.
+
+For example:
+
+```go
+type Strategy struct {
+    // The Debug field will be serialized to JSON with "debug" as the key.
+    Debug bool `json:"debug"`
+}
+```
+
+This utility is located in `github.com/c9s/bbgo/pkg/dynamic`, and the style configuration can be found in `github.com/c9s/bbgo/pkg/style`.
+
+To output the configuration, use `dynamic.PrintConfig`, which only serializes fields that can be marshaled into JSON:
+
+```go
+import (
+    "io"
+    "github.com/c9s/bbgo/pkg/dynamic"
+    "github.com/c9s/bbgo/pkg/interact"
+    "github.com/jedib0t/go-pretty/v6/table"
+)
+
+func (s *Strategy) Print(f io.Writer, pretty bool, withColor ...bool) {
+    var tableStyle *table.Style
+    if pretty {
+        tableStyle = style.NewDefaultTableStyle()
+    }
+    dynamic.PrintConfig(s, f, tableStyle, len(withColor) > 0 && withColor[0], dynamic.DefaultWhiteList()...)
+}
+```
+
+We can now register a command to allow users to interact with the strategy:
+
+```go
+import (
+    "bytes"
+    "github.com/c9s/bbgo/pkg/bbgo"
+    "github.com/c9s/bbgo/pkg/interact"
+)
+
+...
+bbgo.RegisterCommand("/config", "Show latest config", func(reply interact.Reply) {
+    var buffer bytes.Buffer
+    s.Print(&buffer, false)
+    reply.Message(buffer.String())
+})
+```
+
+To dump all strategy fields, you can use `dynamic.ParamDump`. If certain fields should be excluded, simply add the `ignore: "true"` tag to the field definition.
+
+To make fields modifiable, use the `modifiable: "true"` tag and call `bbgo.RegisterModifier(s)` to enable editing. This will automatically add `/modify` commands to the strategy.