docs: fix issue with headers in json parser example

[belczyk]

This PR is fixing two minor issues with Json Parser Example.

1. Sections headers were merged with the last paragraph of previous section (see before and after screenshots below)
2. There were ~40 non-ASCII spaces (character 0+00a0), I replaced them with ASCII spaces

Section headers before:

Section headers after:

Non-ASCII spaces:

[belczyk]

I'm not sure what is going on with ubuntu-latest build, I tried to read output but I didn't find anything indicating how I broke the build.

Does anybody have any insights?

[dsyme]

@kkm000 Can you look at this?

[belczyk]

I think this part might be relevant:

Script reported an error:
-> FileLoadException: Could not load file or assembly 'Microsoft.Build.Framework, Version=15.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. General Exception (0x80131500)
-> Could not load 'Microsoft.Build.Framework, Version=15.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.```