[Docs] Building ESPeasy using PlatformIO in VS-Code

As discussed on the [Forum](https://www.letscontrolit.com/forum/viewtopic.php?f=6&t=6922&p=38512#p38512)

docs/source/Participate/PlatformIO.rst

@@ -0,0 +1,112 @@
+PlatformIO
+**********
+
+ESP easy can be built using the Arduino IDE or PlatformIO (PIO).
+Arduino IDE is not being used during development, so it may take some more effort to get it setup for building ESPeasy.
+
+We advice to use PlatformIO as build environment.
+
+PlatformIO is just the build, test and upload environment for many micro controllers like the ESP8266 and ESP32 we use.
+
+On top of that you need to use an editor, or so called IDE in which PlatformIO will be used.
+
+The two main choices are:
+
+* Atom
+* Microsoft Visual Studio Code. (MS VS-Code)
+
+Both are free to use and are available for Windows, MacOS and Linux.
+
+Apart from these two, there are more available, like Eclipse and probably more.
+
+PlatformIO with Atom
+====================
+
+
+
+PlatformIO with VS-Code
+=======================
+
+install
+-------
+
+For development of ESPeasy, a number of extensions has to be installed in VS-Code:
+
+* PlatformIO IDE (by PlatformIO)
+* C/C++ IntelliSense (by Microsoft)
+* Arduino for Visual Studio Code (by Microsoft)
+* Uncrustify (by Laurent Tréguier)
+
+Uncrustify
+----------
+
+The extension Uncrustify is mainly to format the code using a standard code format definition.
+This code format standard is defined in the file uncrustify.cfg in the main directory of this repository.
+For new code contributions, it is highly appreciated if the code is formatted using this tool.
+
+To do so:
+
+* Right click mouse in editor
+* "Format Document"
+
+The first time (after installing uncrustify) it must be confirmed to use Uncrustify as formatter and using the default suggested config file.
+
+
+Load a project using PlatformIO
+-------------------------------
+
+If you have PIO installed and the source tree cloned to your hard drive, then you can open the main dir of the repository.
+The main directory of the repository is the level with platformio.ini in it.
+
+Then in a few moments after opening the directory, on the left there will appear an alien logo, the logo of PlatformIO.
+If you click that one, you will get a tree with lots and lots of project tasks and environments.
+
+It is important  to note that PlatformIO does everything based on environments, which are defined in the platformio.ini file.
+In the PlatformIO menu (on the left) everything is grouped per environment.
+
+An environment entry has several tasks, like:
+
+* Build
+* Upload
+* Monitor
+* Upload and Monitor
+* ... many more.
+
+Some of these options only are available when you have registered with PlatformIO and some are only for paid subscriptions.
+At least the basic ones used for almost any user are available with the free account.
+
+The environment definitions all have at least the used micro controller in the name and the amount of flash memory used.
+
+For example:
+
+* ..._ESP8266_4M -> ESP8266 has external flash, which can vary in size from 512 kB to 16 MB.
+* ..._ESP8285_1M -> ESP8285 has the flash internal, so is always 1 MB.
+* ..._ESP32_1M8_partition -> ESP32 with 4 MB flash and a 1.8 MB partition for the sketch.
+
+Make a custom build using PlatformIO
+------------------------------------
+
+The easiest is to go for the environment "env:custom_ESP8266_4M" and unfold that one.
+Then select "Build" to see if it will start building.
+
+If that's working, you can open the file "pre_extra_script.py" and add or remove the plugins and controllers you need.
+That Python file is used in the "env:custom_ESP8266_4M" to define what should be embedded and what not.
+
+For example to have only the controller "C014", you can remove "CONTROLLER_SET_ALL", and just add "USES_C014", 
+The same for the plugins you need.
+
+The file is built in the ".pio/build/...." directory right under the main repository directory (the one with the platformio.ini in it)
+
+All builds will be made in a directory with the same name as the environment used.
+
+
+
+Upload to ESP
+=============
+
+
+
+Linux
+-----
+
+For Linux, you may need to install 99-platformio-udev.rules to make PlatformIO upload tools work in vscode.

docs/source/index.rst

@@ -27,6 +27,7 @@ Welcome to ESP Easy's documentation!
    :maxdepth: 2
    :caption: Appendix
 
+   Participate/PlatformIO.rst
    Participate/Documentation.rst
    Reference/Safety.rst
    Reference/Command.rst