Add ADC helper class for STM32F769I

[josesimoes]

Description

• Add ADC helper class for STM32F769I
• Update AppVeyor yaml to skip build on changes to .cs files (don't make sense in this repo as they are only helper classes)

Motivation and Context

• Improves usability by providing C# developers working with the platform with ready to use details on the ADC configuration

How Has This Been Tested?

Screenshots

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Signed-off-by: josesimoes jose.simoes@eclo.solutions

[nfbot]

Hi @josesimoes,

I'm nanoFramework bot.
Thank you for your contribution!

A human will be reviewing it shortly. 😉

[josesimoes]

Focus on STM32F769I_DISCOVERY.Adc.cs
This is my suggestion to document and provide C# developers an insight on ADC configuration for this board.

The idea would be to provide such a file for every reference board.

Plus we should have one of these for each peripheral that is not self-documenting (Serial for example, you just need to query the providers and then call the COM that you want, no need for any further details).

[steffalk]

I welcome such enumerations highly, and really would see them for a) all boards supported (even if I have only a Netduino 3 so far) and b) for all things where a (newbie) developer/hobbyist would search forever for the needed information. The same is what I went through and only could succeed with the help from Peter and José about mapping a Netduino 3 I/O pin label to the actual integer number to use in C# code.

Please do include them even for cases where a µC professional wouldn't need it. Think about the entry-level hobbyists with want to start there nanoframework journey and make that start as easy as possible and as not frustrating as possible.

[josesimoes]

@piwi1263 and @AdrianSoundy are we good with this? can it be replicated for other targets/peripherals?