Add consumerProguardFiles into aar

Author: YvesCheung

Diff for: README.md

@@ -17,7 +17,7 @@ implementation 'io.nano:android-tex:1.0.0'
 Add the following rule to your proguard config file:
 
 ```
--keep class io.nano.tex.**
+-keep class io.nano.tex.** {*;}
 ```
 
 # How to use

Diff for: libtex/build.gradle

@@ -17,12 +17,13 @@ android {
         targetSdkVersion compileSdk
         versionCode 1
         versionName "1.0.0"
+
+        consumerProguardFiles 'consumer-rules.pro'
     }
 
     buildTypes {
         release {
             minifyEnabled false
-            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }
 

Diff for: libtex/proguard-rules.pro renamed to libtex/consumer-rules.pro

@@ -19,3 +19,4 @@
 # If you keep the line number information, uncomment this to
 # hide the original source file name.
 #-renamesourcefileattribute SourceFile
+-keep class io.nano.tex.** {*;}