Updated to fix issues I experienced on MacOS

Updated the image links in the app.py file, updated the dockerfile commands to latest alpine version and working pip command.

beginner/chapters/webapps.md

@@ -202,18 +202,8 @@ app = Flask(__name__)
 
 # list of cat images
 images = [
-   "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr05/15/9/anigif_enhanced-buzz-26388-1381844103-11.gif",
-    "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr01/15/9/anigif_enhanced-buzz-31540-1381844535-8.gif",
-    "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr05/15/9/anigif_enhanced-buzz-26390-1381844163-18.gif",
-    "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr06/15/10/anigif_enhanced-buzz-1376-1381846217-0.gif",
-    "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr03/15/9/anigif_enhanced-buzz-3391-1381844336-26.gif",
-    "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr06/15/10/anigif_enhanced-buzz-29111-1381845968-0.gif",
-    "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr03/15/9/anigif_enhanced-buzz-3409-1381844582-13.gif",
-    "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr02/15/9/anigif_enhanced-buzz-19667-1381844937-10.gif",
-    "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr05/15/9/anigif_enhanced-buzz-26358-1381845043-13.gif",
-    "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr06/15/9/anigif_enhanced-buzz-18774-1381844645-6.gif",
-    "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr06/15/9/anigif_enhanced-buzz-25158-1381844793-0.gif",
-    "http://img.buzzfeed.com/buzzfeed-static/static/2013-10/enhanced/webdr03/15/10/anigif_enhanced-buzz-11980-1381846269-1.gif"
+   "https://cdn.britannica.com/39/7139-050-A88818BB/Himalayan-chocolate-point.jpg",
+    "https://upload.wikimedia.org/wikipedia/commons/thumb/4/4d/Cat_November_2010-1a.jpg/1280px-Cat_November_2010-1a.jpg"
     ]
 
 @app.route('/')
@@ -230,7 +220,7 @@ if __name__ == "__main__":
 In order to install the Python modules required for our app, we need to create a file called **requirements.txt** and add the following line to that file:
 
 ```
-Flask==0.10.1
+Flask==2.3.2
 ```
 
 #### templates/index.html
@@ -271,7 +261,7 @@ Create a directory called `templates` and create an **index.html** file in that
 
 We want to create a Docker image with this web app. As mentioned above, all user images are based on a _base image_. Since our application is written in Python, we will build our own Python image based on [Alpine](https://store.docker.com/images/alpine). We'll do that using a **Dockerfile**.
 
-A [Dockerfile](https://docs.docker.com/engine/reference/builder/) is a text file that contains a list of commands that the Docker daemon calls while creating an image. The Dockerfile contains all the information that Docker needs to know to run the app — a base Docker image to run from, location of your project code, any dependencies it has, and what commands to run at start-up. It is a simple way to automate the image creation process. The best part is that the [commands](https://docs.docker.com/engine/reference/builder/) you write in a Dockerfile are *almost* identical to their equivalent Linux commands. This means you don't really have to learn new syntax to create your own Dockerfiles.
+A [Dockerfile](https://docs.docker.com/engine/reference/builder/) is a text/Document file that contains a list of commands that the Docker daemon calls while creating an image. The Dockerfile contains all the information that Docker needs to know to run the app — a base Docker image to run from, location of your project code, any dependencies it has, and what commands to run at start-up. It is a simple way to automate the image creation process. The best part is that the [commands](https://docs.docker.com/engine/reference/builder/) you write in a Dockerfile are *almost* identical to their equivalent Linux commands. This means you don't really have to learn new syntax to create your own Dockerfiles.
 
 
 1. Create a file called **Dockerfile**, and add content to it as described below.
@@ -279,13 +269,13 @@ A [Dockerfile](https://docs.docker.com/engine/reference/builder/) is a text file
   We'll start by specifying our base image, using the `FROM` keyword:
 
   ```
-  FROM alpine:3.5
+  FROM alpine:latest
   ```
 
 2. The next step usually is to write the commands of copying the files and installing the dependencies. But first we will install the Python pip package to the alpine linux distribution. This will not just install the pip package but any other dependencies too, which includes the python interpreter. Add the following [RUN](https://docs.docker.com/engine/reference/builder/#run) command next:
 
   ```
-  RUN apk add --update py2-pip
+  RUN apk add --update py-pip
   ```
 
 3. Let's add the files that make up the Flask Application.
@@ -327,7 +317,7 @@ A [Dockerfile](https://docs.docker.com/engine/reference/builder/) is a text file
   FROM alpine:3.5
 
   # Install python and pip
-  RUN apk add --update py2-pip
+  RUN apk add --update py-pip
 
   # install Python modules needed by the Python app
   COPY requirements.txt /usr/src/app/