docs: added change for the upcoming v4 release

[ci skip]

README.md

@@ -578,6 +578,7 @@ If you want to debug a test you should use `gulp test-without-coverage` to run a
       *(Thanks to @stevage for pointing out the effect of the breaking change in [issue #131](https://github.com/request/request-promise/issues/131))*
     - Resolved issues [#65](https://github.com/request/request-promise/issues/65) and [#71](https://github.com/request/request-promise/issues/71) by publishing nearly identical libraries to support other Promise implementations: [`request-promise-native`](https://github.com/request/request-promise-native) and [`request-promise-any`](https://github.com/request/request-promise-any)
       *(Thanks to @benjamingr, @eilgin, @gillesdemey, @hildjj, @iggycoloma, @jonathanong, @knpwrs, @MarkHerhold, @massimocode, @mikeal, @niftylettuce, @raitucarp, @sherdeadlock, @tonylukasavage, and @vgoloviznin for the valuable discussions!)*
+    - Relicensed this library with the ISC license
 - v3.0.0 (2016-04-16)
     - **Breaking Change**: Overhauled the handling of the `transform` function
       *(Thanks to @Limess for explaining the need in [issue #86](https://github.com/request/request-promise/issues/86))*