added user signup feature

internal/model/book.go

@@ -0,0 +1,10 @@
+package model
+
+import "gorm.io/gorm"
+
+type Book struct {
+	gorm.Model
+	Title  string `json:"title" gorm:"not null"`
+	Author string `json:"author"`
+	Rating int    `json:"rating"`
+}