Updated ContributorGuidelines (markdown)

ContributorGuidelines.md

@@ -7,8 +7,8 @@ Please read the [MicroPython Code of Conduct](https://github.com/micropython/mic
 We welcome all types of contributions, across a wide variety of different domains.
 
 * The core Python virtual machine and runtime
-* The built-in standard library
-* The "MicroPython Library" (see https://github.com/micropython/micropython-lib)
+* The standard library and MicroPython-specific built-ins
+* The ["MicroPython Library"](https://github.com/micropython/micropython-lib)
 * Ports to different architectures and microcontrollers
 * Board definitions
 * Documentation
@@ -36,7 +36,7 @@ In many cases, features can be enabled conditionally for a given target (i.e. bo
 To give you an idea of how highly we value code size, the MicroPython team will spent hours of effort just to save 10's of bytes from a given feature. This unfortunately means that the code is more complicated, but it's a worthwhile trade-off.
 
 ## Ports
-We welcome ports to new architectures and microcontroller families. However, not all ports can be accepted into the main repository as each port is a significant maintenance overhead for the core team. It is straightforward to maintain an "out-of-tree" port using MicroPython as a submodule.
+We welcome ports to new architectures and microcontroller families. However, not all ports can be accepted into the main repository as each port is a significant maintenance overhead for the core team. It is straightforward to maintain a third-party "out-of-tree" port using MicroPython as a submodule.
 
 ## Board definitions
 Each port contains a set of board definitions. Each one of these boards will be compiled automatically and published on the [downloads page](https://micropython.org/download/). Board definitions will typically also require a thumbnail image to be added to the [MicroPython media repository](https://github.com/micropython/micropython-media) via a PR.