Update documentation

**Describe the bug**
In this part 
https://github.com/project-SIMPLE/simple.webplatform?tab=readme-ov-file#installation
in seems that the user must modify something in its .env

which is written like this "update according to your value"

it needs to be MORE EXPLICIT

what need to be changed? 

```
#EXTRA_LEARNING_PACKAGE_PATH="/uncommment/and/set/another/path/to/check
```
