Updated README.md to clarify NDK versions (#1981)

* 📚 Updated README.dm to clarify NDK versions

* 🔧 Change back to r19b

README.md

@@ -92,33 +92,33 @@ Please refer to the LICENSE file.
 
 ## History
 
-In 2015 these tools were rewritten to provide a new, easier to use and
-extend interface. If you'd like to browse the old toolchain, its
+In 2015 these tools were rewritten to provide a new, easier-to-use and
+easier-to-extend interface. If you'd like to browse the old toolchain, its
 status is recorded for posterity at at
 https://github.com/kivy/python-for-android/tree/old_toolchain.
 
-In the last quarter of 2018 the python recipes has been changed, the
-new recipe for python3 (3.7.1) has a new build system which has been
+In the last quarter of 2018 the python recipes were changed. The
+new recipe for python3 (3.7.1) had a new build system which was
 applied to the ancient python recipe, allowing us to bump the python2
-version number to 2.7.15. This change, unifies the build process for
-both python recipes, and probably solve some issues detected over the
-years. Also should be mentioned that this **unified python recipes**
-require to target to a **minimum api level of 21**,
-*Android 5.0 - Lollipop*, so in case the you need to build targeting an
-api level below 21, you must use an old version of python-for-android
-(<=0.7.1). All this work has been done using android ndk version r17c,
-and your build should success with that version...but be aware that the
-project is in constant development so, as per time of writing,
-``we recommend to use android's NDK r19b`` because the toolchains installed by
-default with the NDK may be used *in-place* and the python-for-android project
-has been adapted to that feature, so, it's mandatory to use, at least, ndk
-version r19 (be aware that more modern versions of the
-android's ndk may not work).
+version number to 2.7.15. This change unified the build process for
+both python recipes, and probably solved various issues detected over the
+years. It should also be mentioned that these **unified python recipes**
+require a **minimum target api level of 21**,
+*Android 5.0 - Lollipop*, so in the case that you need to build targeting an
+api level below 21, you should use an older version of python-for-android
+(<=0.7.1).
+
+Be aware that this project is in constant development so, as per time of writing,
+you should use a minimum on Android's NDK r19, and ``we recommend using NDK r19b``.
+This is because the toolchains installed by
+default with the NDK can be used *in-place* and the python-for-android project
+has been adapted for that feature. Also be aware that more recent versions of the
+Android's NDK may not work.
 
 Those mentioned changes has been done this way to make easier the transition
 between python3 and python2. We will slowly phase out python2 support
 towards 2020...so...if you are using python2 in your projects you should
-consider to migrate it into python3.
+consider migrating it into python3.
 
 ## Contributors