v1.5.0 to fix multiple-definitions linker error

#### Releases v1.5.0

1. Fix multiple-definitions linker error.
2. Add example [multiFileProject](examples/multiFileProject) to demo for multiple-file project to avoid `multiple-definitions` linker error

Author: khoih-prog

CONTRIBUTING.md

@@ -14,8 +14,8 @@ If you don't find anything, please [open a new issue](https://github.com/khoih-p
 
 Please ensure to specify the following:
 
-* Arduino IDE version (e.g. 1.8.16) or Platform.io version
-* Board Core Version (e.g. ESP32 core v2.0.1)
+* Arduino IDE version (e.g. 1.8.19) or Platform.io version
+* Board Core Version (e.g. ESP32 core v2.0.3)
 * 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:
@@ -26,11 +26,11 @@ Please ensure to specify the following:
 ### Example
 
 ```
-Arduino IDE version: 1.8.16
+Arduino IDE version: 1.8.19
 WT32_ETH01 board
-ESP32 core v2.0.1
+ESP32 core v2.0.3
 OS: Ubuntu 20.04 LTS
-Linux xy-Inspiron-3593 5.4.0-90-generic #101-Ubuntu SMP Fri Oct 15 20:00:55 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
+Linux xy-Inspiron-3593 5.13.0-51-generic #58~20.04.1-Ubuntu SMP Tue Jun 14 11:29:12 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
 
 Context:
 I encountered a crash while trying to use the Timer Interrupt.
@@ -50,3 +50,4 @@ There are usually some outstanding feature requests in the [existing issues list
 ### Sending Pull Requests
 
 Pull Requests with changes and fixes are also welcome!
+