Update README with Build Instructions

[JoelProminic]

We noticed that the README does not have any build instructions for this application. @Aszusz needed these instructions for testing some Moonshine Website changes.

[rat-moonshine]

A short build-instruction being added. @Aszusz let me know if it is adequate for your needs.

[Aszusz]

@rat-moonshine
I tried on both Win and macOS and both failed for me. I'm focusing on macOS right now, it seems to be the easier one.

1. In ApplicationProperties.xml should the path go inside CDATA or instead of CDATA? This seems to be correct but I need to make sure first:

<unixSDKPath><![CDATA[/Users/aszusz/Downloads/MoonshineSDKs/Flex_SDK/Flex_4.16.1_AIR_33.1]]></unixSDKPath>

2. The build fails for me with this error:

CompileSWF:
     [echo] bin-debug/MoonshineSDKInstaller.swf
    [mxmlc] Loading configuration file /Users/aszusz/Downloads/MoonshineSDKs/Flex_SDK/Flex_4.16.1_AIR_33.1/frameworks/air-config.xml
    [mxmlc] Error: null
    [mxmlc] 

BUILD FAILED
/Volumes/Data/home/repos/for-prominic/Moonshine-SDK-Installer/MoonshineSDKInstaller/build/build.xml:211: The following error occurred while executing this line:
/Volumes/Data/home/repos/for-prominic/Moonshine-SDK-Installer/MoonshineSDKInstaller/build/build.xml:636: mxmlc task failed.

Total time: 14 seconds

It seems to get the path right. I checked and /frameworks/air-config.xml exists and seems to be alright.

[rat-moonshine]

@Aszusz

1. Yes, any value should go inside <![CDATA[...]>
2. Can you please share full log details? You can send it in an email

I assume you've checkout the complete Moonshine-SDK-Installer repository before you start a build.

[JoelProminic]

@Aszusz, did you check the full path (/Users/aszusz/Downloads/MoonshineSDKs/Flex_SDK/Flex_4.16.1_AIR_33.1/frameworks/air-config.xml) or just check for frameworks/air-config.xml in the SDK? My initial instinct is that there is some typo in the full path. I confirmed that ~/Downloads/MoonshineSDKs/Flex_SDK/Flex_4.16.1_AIR_33.1/frameworks/air-config.xml is the MSDKI standard, though.