Added version release notes.

Further stylizes the project.

[ci skip]

.ruby-version

@@ -1 +1 @@
-2.6.0
+2.6.3

CHANGES.md

@@ -1,3 +1,14 @@
+# 7.1.1 (2019-05-01)
+
+- Added project icon to README.
+- Updated to Ruby 2.6.3.
+
+# 7.1.0 (2019-04-01)
+
+- Added XCode installer fix to troubleshooting section.
+- Updated to Ruby 2.6.1.
+- Updated to Ruby 2.6.2.
+
 # 7.0.0 (2019-01-01)
 
 - Fixed Circle CI cache for Ruby version.

README.md

@@ -1,3 +1,7 @@
+<p align="center">
+  <img src="mac_os.png" alt="MacOS Icon"/>
+</p>
+
 # macOS
 
 [![Circle CI Status](https://circleci.com/gh/bkuhlmann/mac_os.svg?style=svg)](https://circleci.com/gh/bkuhlmann/mac_os)
@@ -72,7 +76,7 @@ Current Version (stable):
 
     git clone https://github.com/bkuhlmann/mac_os.git
     cd mac_os
-    git checkout 7.0.0
+    git checkout 7.1.1
 
 Master Version (unstable):
 
@@ -179,13 +183,20 @@ project is built upon the functions found in the `lib` folder. See the
 
 ## Troubleshooting
 
-When using the boot disk, you might experience a situation where you see a black screen with a white
-circle and diagonal line running through it. This means macOS lost or can't find the boot disk for
-some reason. To correct this, shut down and boot up the system again while holding down the
-`OPTION+COMMAND+R+P` keys simultaneously. You might want to wait for the system boot sound to happen
-a few times before releasing the keys. This will clear the system NVRAM/PRAM. At this point you can
-shut down and restart the system following the boot disk instructions (the boot disk will be
-recognized now).
+- When using the boot disk, you might experience a situation where you see a black screen with a
+  white circle and diagonal line running through it. This means macOS lost or can't find the boot
+  disk for some reason. To correct this, shut down and boot up the system again while holding down
+  the `OPTION+COMMAND+R+P` keys simultaneously. You might want to wait for the system boot sound to
+  happen a few times before releasing the keys. This will clear the system NVRAM/PRAM. At this point
+  you can shut down and restart the system following the boot disk instructions (the boot disk will
+  be recognized now).
+- Sometimes, when installing XCode development tools (i.e. the `t` option), not all of the macOS
+  headers will be installed. This can cause issues with compiling and building native packages. For
+  example: `fatal error: 'stdio.h' file not found`. This can happen due to an intermittent bug with
+  the XCode installer. To fix this, you'll need to install this package:
+  `/Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg`. Depending on
+  your system, the version might differ, so look for a `*.pkg` in the
+  `/Library/Developer/CommandLineTools/Packages` folder.
 
 ## Versioning