Add ReadMe for third party port contributions (FreeRTOS#371)

* Add ReadMe for third party port contributions

Signed-off-by: Gaurav Aggarwal <[email protected]>

Author: aggarg

portable/ThirdParty/README.md

@@ -0,0 +1,48 @@
+# FreeRTOS Third Party Ports
+
+FreeRTOS third party ports can be supported by the FreeRTOS team, a FreeRTOS
+partner or FreeRTOS community members. Depending on who supports it, the support
+provided will differ as follows:
+
+## FreeRTOS Team Supported Third Party FreeRTOS Ports
+
+Location: https://github.com/FreeRTOS/FreeRTOS-Kernel/tree/main/portable/ThirdParty
+
+These third party FreeRTOS ports are supported by the FreeRTOS team. For a
+FreeRTOS team supported third party FreeRTOS port:
+
+* The code has been reviewed by the FreeRTOS team.
+* FreeRTOS team has access to the hardware and the test results have been
+  verified by the FreeRTOS team. 
+* Customer queries as well as bugs are addressed by the FreeRTOS team.
+
+A new FreeRTOS port cannot be directly contributed to this location. Instead,
+the FreeRTOS team will decide to take ownership of a partner supported or a
+community supported FreeRTOS port based on the community interest.
+
+## Partner Supported FreeRTOS Ports
+
+Location: https://github.com/FreeRTOS/FreeRTOS-Kernel-Partner-Supported-Ports/tree/main
+
+These FreeRTOS ports are supported by a FreeRTOS partner. For a partner
+supported FreeRTOS port:
+
+* The code has not been reviewed by the FreeRTOS team.
+* FreeRTOS team has not verified the tests results but tests exist and are
+  reported to be successful by the partner. 
+* Customer queries as well as bugs are addressed by the partner.
+* A new FreeRTOS port can be directly contributed by a partner. The process to
+contribute a FreeRTOS port is documented [here](https://github.com/FreeRTOS/FreeRTOS-Kernel-Partner-Supported-Ports/blob/main/README.md).
+
+## Community Supported FreeRTOS Ports
+
+Location: https://github.com/FreeRTOS/FreeRTOS-Kernel-Community-Supported-Ports/tree/main
+
+These FreeRTOS ports are supported by the FreeRTOS community members. For a
+community supported FreeRTOS port:
+
+* The code has not been reviewed by the FreeRTOS team.
+* Tests may or may not exist for the FreeRTOS port.
+* Customer queries as well as bugs are addressed by the community.
+* A new FreeRTOS port can be directly contributed by anyone. The process to
+contribute a FreeRTOS port is documented [here](https://github.com/FreeRTOS/FreeRTOS-Kernel-Community-Supported-Ports/blob/main/README.md).