doc: added types to be generated section

README.md

@@ -103,48 +103,73 @@ For the actual generated code, see the [example](https://github.com/miyamo2/filt
 
 ## Features
 
+### Types to be generated
+
+`filtgen` generates the following defined-types.  
+Type name is determined by the struct name; e.g. `User` -> `UserSlice`.  
+To use the generated methods, cast must be performed.
+```go
+s := []User{
+    {Name: "Alice"},
+    {Name: "Bob"},
+}
+for i, v := range UserSlice(s).NameEq("Alice") {
+    fmt.Printf("%d: %s\n", i, v.Name)
+}
+```
+
+`XxxSlice`(`[]T`)
+
+`XxxMap[K]`(`map[K compareble]T`)
+
+`XxxSeq[T]`(`iter.Seq[T]`)
+
+`XxxSeq2[T]`(`iter.Seq2[T, U]`)
+
+### Methods to be generated
+
 Following methods are generated by `filtgen`.  
 Method name is determined by the field name; e.g. `Name` -> `NameEq`.
 
-### `XxxEq`
+#### `XxxEq`
 
 Selects iterator items whose field values are equal to the specified value.
 
-### `XxxNe`
+#### `XxxNe`
 
 Selects iterator items whose field values are not equal to the specified value.
 
-### `XxxGt`
+#### `XxxGt`
 
 Selects iterator items whose field values are greater than the specified value.
 
-### `XxxLt`
+#### `XxxLt`
 
 Selects iterator items whose field values are less than the specified value.
 
-### `XxxGe`
+#### `XxxGe`
 
 Selects iterator items whose field values are greater than or equal to the specified value.
 
-### `XxxLe`
+#### `XxxLe`
 
 Selects iterator items whose field values are less than or equal to the specified value.
 
-### `XxxMatches`
+#### `XxxMatches`
 
 Selects iterator items whose field values match the specified function.
 
-### `XxxIs`
+#### `XxxIs`
 
 Selects iterator items whose field values are equal to the specified `error`.  
 Equivalence is determined by `errors.Is`.
 
-### `XxxIsnt`
+#### `XxxIsnt`
 
 Selects iterator items whose field values are not equal to the specified `error`.
 Equivalence is determined by `errors.Is`.
 
-## List of compatible filters by type
+#### List of compatible filters by type
 
 | Type\Filter  | `XxxEq` | `XxxNe` | `XxxGt` | `XxxLt` | `XxxGe` | `XxxLe` | `XxxMatches` | `XxxIs` | `XxxIsnt` |
 |--------------|---------|---------|---------|---------|---------|---------|--------------|---------|-----------|
@@ -169,7 +194,7 @@ Equivalence is determined by `errors.Is`.
 | `bool`       | ✅       | ✅       | ❌       | ❌       | ❌       | ❌       | ✅            | ❌       | ❌         |
 | other-types  | ❌       | ❌       | ❌       | ❌       | ❌       | ❌       | ✅            | ❌       | ❌         |
 
-## `filtgen` tags
+### `filtgen` tags
 
 The following values can be set in the `filtgen` tag.  
 If you want to set multiple values, separate them with `,`.