Installation instructions & First run - Improvements

Referencing the official guide: [https://emscripten.org/docs/getting_started/downloads.html](https://emscripten.org/docs/getting_started/downloads.html)

Some of the parts of the page are confusing and ordered so that it is easy to make mistakes.

To make it easier to start with emscripten I would suggest for the following improvements to be made:

_1. In Run the following emsdk commands section:_

Mark CLEARLY the first commands window as Linux/Mac:

---
### Getting the tools
To get the latest tools from GitHub and set them as active run the following.

**Linux/Mac**

```
#Fetch the latest version of the emsdk (not needed the first time you clone)
git pull

# Download and install the latest SDK tools.
./emsdk install latest

# Make the "latest" SDK "active" for the current user. (writes .emscripten file)
./emsdk activate latest

# Activate PATH and other environment variables in the current terminal
source ./emsdk_env.sh
```
**Windows**

```
#Fetch the latest version of the emsdk (not needed the first time you clone)
git pull

# Download and install the latest SDK tools.
emsdk.bat install latest

# Make the "latest" SDK "active" for the current user. (writes .emscripten file)
emsdk.bat activate latest

# Activate PATH and other environment variables in the current terminal (optional)
emsdk_env.bat
```
---

Remove the (now unnecessary) notes that were under the instructions.

_2. For Windows machines optionally add the following missing step:_

```
# To open the emscripten command line in your IDE terminal run the following
# navigate to newly created emsdk folder
cd emsdk

# run the emcmdprompt.bat file
emcmdprompt.bat

# to use the compilation commands remember to navigate one folder up
cd..
```
---

I would be grateful for this changes to be made in the guide. Have these been present earlier, it would have made my life so much easier.

Thank you,
Sonia