Use explicit imports in README.md and Vector-Search-City.ipynb

Author: greenrobot

README.md

@@ -43,7 +43,7 @@ Code Example: CRUD (Create, Read, Update, Delete)
 What does using ObjectBox in Python look like?
 
 ```python
-from objectbox import *
+from objectbox import Entity, Id, Store, String
 
 @Entity()
 class Person:

example/vectorsearch-cities-notebook/Vector-Search-City.ipynb

@@ -67,7 +67,7 @@
         }
       ],
       "source": [
-        "!pip install --upgrade --pre objectbox"
+        "!pip install --upgrade objectbox"
       ]
     },
     {
@@ -86,7 +86,7 @@
     {
       "cell_type": "code",
       "source": [
-        "from objectbox import *\n",
+        "from objectbox import Entity, Float32Vector, HnswIndex, Id, Store, String\n",
         "\n",
         "@Entity()\n",
         "class City:\n",
@@ -619,4 +619,4 @@
       "outputs": []
     }
   ]
-}
+}