Update README.md (#3737)

Replace a confusing sentence with a clear one. Fix grammatical errors.

README.md

@@ -6,14 +6,14 @@
 
 ### Just a heads up: Charts 3.0 has some breaking changes. Please read [the release/migration notes](https://github.com/danielgindi/Charts/releases/tag/v3.0.0). 
 ### Another heads up: ChartsRealm is now in a [separate repo](https://github.com/danielgindi/ChartsRealm). Pods is also now `Charts` and `ChartsRealm`, instead of ~`Charts/Core`~ and ~`Charts/Realm`~
-### One more heads up: As Swift evolves, if you are not using latest Swift compiler, you shouldn't check out master branch. Instead, you should go to release page and pick up whatever suits you.
+### One more heads up: As Swift evolves, if you are not using the latest Swift compiler, you shouldn't check out the master branch. Instead, you should go to the release page and pick up whatever suits you.
 
 * Xcode 10.0 / Swift 4.2 (master branch)
 * iOS >= 8.0 (Use as an **Embedded** Framework)
 * tvOS >= 9.0
 * macOS >= 10.11
 
-Okay so there's this beautiful library called [MPAndroidChart](https://github.com/PhilJay/MPAndroidChart) by [Philipp Jahoda](https://www.linkedin.com/in/philippjahoda) which has become very popular amongst Android developers, and in the meanwhile there's no decent charting solution for iOS.
+Okay so there's this beautiful library called [MPAndroidChart](https://github.com/PhilJay/MPAndroidChart) by [Philipp Jahoda](https://www.linkedin.com/in/philippjahoda) which has become very popular amongst Android developers, but there was no decent solution to create charts for iOS.
 
 I've chosen to write it in `Swift` as it can be highly optimized by the compiler, and can be used in both `Swift` and `ObjC` project. The demo project is written in `ObjC` to demonstrate how it works.