DOCS: Fixing formatting in Samples - port to master (#13128)

* DOCS: Fixing formatting in Samples - porting to master

Porting
https://github.com/openvinotoolkit/openvino/pull/13085

Fixing incorrectly numbered lists and indentation of code blocks.

* Update get_started_demos.md

Co-authored-by: Maciej Smyk <maciejx.smyk@intel.com>

samples/cpp/classification_sample_async/README.md

@@ -83,28 +83,24 @@ To run the sample, you need specify a model and image:
 ### Example
 
 1. Install the `openvino-dev` Python package to use Open Model Zoo Tools:
-
-```
-python -m pip install openvino-dev[caffe,onnx,tensorflow2,pytorch,mxnet]
-```
+   ```
+   python -m pip install openvino-dev[caffe,onnx,tensorflow2,pytorch,mxnet]
+   ```
 
 2. Download a pre-trained model using:
-
-```
-omz_downloader --name googlenet-v1
-```
+   ```
+   omz_downloader --name googlenet-v1
+   ```
 
 3. If a model is not in the IR or ONNX format, it must be converted. You can do this using the model converter:
-
-```
-omz_converter --name googlenet-v1
-```
+   ```
+   omz_converter --name googlenet-v1
+   ```
 
 4. Perform inference of `dog.bmp` using `googlenet-v1` model on a `GPU`, for example:
-
-```
-classification_sample_async -m googlenet-v1.xml -i dog.bmp -d GPU
-```
+   ```
+   classification_sample_async -m googlenet-v1.xml -i dog.bmp -d GPU
+   ```
 
 ## Sample Output