v1.0.0 for Teensy41 and QNEthernet

### Initial Releases v1.0.0

1. Initial porting and coding to support **Teensy 4.1 using QNEthernet Library**
2. Add example [multiFileProject](examples/multiFileProject) to demo for multiple-file project to avoid `multiple-definitions` linker error

CONTRIBUTING.md

@@ -0,0 +1,53 @@
+## Contributing to Teensy41_AsyncTCP
+
+### Reporting Bugs
+
+Please report bugs in [Teensy41_AsyncTCP](https://github.com/khoih-prog/Teensy41_AsyncTCP/issues/new) if you find them.
+
+However, before reporting a bug please check through the following:
+
+* [Existing Open Issues](https://github.com/khoih-prog/Teensy41_AsyncTCP/issues) - someone might have already encountered this.
+
+If you don't find anything, please [open a new issue](https://github.com/khoih-prog/Teensy41_AsyncTCP/issues/new).
+
+### How to submit a bug report
+
+Please ensure to specify the following:
+
+* Arduino IDE version (e.g. 1.8.19) or Platform.io version
+* `Teensyduino` Core Version (e.g. Teensy core v1.56)
+* Contextual information (e.g. what you were trying to achieve)
+* Simplest possible steps to reproduce
+* Anything that might be relevant in your opinion, such as:
+  * Operating system (Windows, Ubuntu, etc.) and the output of `uname -a`
+  * Network configuration
+
+
+### Example
+
+```
+Arduino IDE version: 1.8.19
+Teensyduino Core Version 1.56
+OS: Ubuntu 20.04 LTS
+Linux xy-Inspiron-3593 5.13.0-35-generic #40~20.04.1-Ubuntu SMP Mon Mar 7 09:18:32 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
+
+Context:
+I encountered an endless loop while trying to connect to Local WiFi.
+
+Steps to reproduce:
+1. ...
+2. ...
+3. ...
+4. ...
+```
+
+### Sending Feature Requests
+
+Feel free to post feature requests. It's helpful if you can explain exactly why the feature would be useful.
+
+There are usually some outstanding feature requests in the [existing issues list](https://github.com/khoih-prog/Teensy41_AsyncTCP/issues?q=is%3Aopen+is%3Aissue+label%3Aenhancement), feel free to add comments to them.
+
+### Sending Pull Requests
+
+Pull Requests with changes and fixes are also welcome!
+