Update the links to KumaScript macros in the Yari repo. (#2888)

README.md

@@ -669,20 +669,19 @@ KumaScript macros are still used on MDN pages, even in the new platform.
 These are the function names surrounded by handlebars-style double curly
 braces that you'll see in the source code on occasion, for example
 `{{domxref}}` Eventually we have to replace them with something else,
-but they are here for now. They live in
-[https://github.com/mdn/yari/tree/master/kumascript/macros](https://github.com/mdn/yari/tree/master/kumascript/macros).
+but they are here for now. They live in <https://github.com/mdn/yari/tree/main/kumascript/macros>.
 
 Sometimes you'll want to make a change to the content that relies on a
 macro change. Take [https://github.com/mdn/content/pull/187](https://github.com/mdn/content/pull/187).
 Florian wanted to add documentation for a new WebGL extension to MDN, but
 this change relied on the new feature's spec being added to
-[https://github.com/mdn/yari/blob/master/kumascript/macros/SpecData.json](https://github.com/mdn/yari/blob/master/kumascript/macros/SpecData.json).
+<https://github.com/mdn/yari/blob/main/kumascript/macros/SpecData.json>.
 If not, the specification table on the new page would not render properly
 because the data it relies on would not be there.
 
 In such situations:
 
-1. Make the required PR to <https://github.com/mdn/yari/blob/master/kumascript/macros/>
+1. Make the required PR to <https://github.com/mdn/yari/tree/main/kumascript/macros>
    first, and get that merged.
 2. Add the content to this repo.