improve readme

README.md

@@ -1,8 +1,6 @@
 # EZ DB
 
-This package provides simple interfaces for working with basic key-value storage in your Go application.
-
-**EZ DB is not a database unto itself.** If you want more control or features, just use the appropriate database software and connector for your needs.
+This package provides simple interfaces for working with basic key-value document storage in your Go application.
 
 ## System requirements
 
@@ -33,22 +31,6 @@ func main() {
 }
 ```
 
-In other cases, such as media stores, you may prefer not to specify a document type. This example allows arbitrary bytes to be written:
-
-```go
-package main
-
-import "github.com/annybs/ezdb"
-
-var db = ezdb.Memory[[]byte](nil)
-
-func main() {
-	db.Open()
-	db.Put("data", []byte("arbitrary bytes"))
-	db.Close()
-}
-```
-
 ## Marshaling data
 
 Some database backends require marshaling and unmarshaling data. The `DocumentMarshaler[T1, T2]` interface allows you to use whatever marshaler suits your needs or the requirements of your chosen database.
@@ -64,6 +46,14 @@ The following databases are included in EZ DB:
 - `LevelDB[T]` is [fast key-value storage](https://github.com/google/leveldb) on disk
 - `Memory[T]` is essentially a wrapper for `map[string]T`. It can be provided another Collection to use as a persistence backend
 
+## Limitations
+
+EZ DB is intended for simple document storage and can work with any addressable data represented as `T` in your Go app.
+
+This makes it unsuited for working with unaddressable types, such as byte arrays, particularly when a document marshaler is involved.
+
+If you want more control beyond what EZ DB offers, it's best to just use the appropriate database software and connector for your needs.
+
 ## License
 
 See [LICENSE.md](./LICENSE.md)

leveldb_test.go

@@ -11,7 +11,7 @@ func TestLevelDB(t *testing.T) {
 		Age  int    `json:"age"`
 	}
 
-	path := ".leveldb/test_json"
+	path := ".leveldb"
 
 	marshaler := JSON(func() *Student {
 		return &Student{}