feat(cache): improve md (#1063)

Co-authored-by: 彭业昌 <refrain@douyu.tv>

website/docs/jupiter/4.9freecache.md

@@ -53,6 +53,7 @@ pkg/cache 包支持多个本地缓存库，并支持metric上报
 ### 2 初始化实例
 ```go
 import (
+ "github.com/douyu/jupiter/pkg/cache"
  "github.com/douyu/jupiter/pkg/cache/xfreecache/v2"
 )
 
@@ -62,7 +63,7 @@ type Student struct {
 }
 
 type Instance struct {
- localCache *xfreecache.LocalCache[string, Student]
+ localCache *cache.Cache[string, Student]
 }
 
 func NewInstance() *Instance {
@@ -134,11 +135,12 @@ package bwlist
 
 import (
  "context"
+ "github.com/douyu/jupiter/pkg/cache"
  "github.com/douyu/jupiter/pkg/cache/xfreecache/v2"
 )
 
 type Instance struct {
- localCache *xfreecache.LocalCache[int32, []int32]
+ localCache *cache.Cache[int32, []int32]
 }
 
 func NewInstance() *Instance {