docs: fixing typos and formating

subjects/java/checkpoints/helloworld/README.md

@@ -33,4 +33,4 @@ $ javac *.java -d build
 $ java -cp build ExerciseRunner
 Hello World !
 $
-```
+```

subjects/java/checkpoints/system-logger/README.md

@@ -33,4 +33,4 @@ $ javac *.java -d build
 $ java -cp build ExerciseRunner
 System Log: message
 $
-```
+```

subjects/java/checkpoints/universal-greeting/README.md

@@ -2,13 +2,12 @@
 
 ### Instructions
 
-In a file named `UniversalGreeting.java` write a function `greeting` that take a String language as parametre and return a greating message based on the language as follows:
+In a file named `UniversalGreeting.java` write a function `greeting` that takes a String language as a parameter and returns a greeting message based on the language as follows:
 
 FR : Bonjour comment allez-vous
 EN : Hello, How are you
 ES : Hola, cómo estás
 
-
 ### Expected Functions
 
 ```java
@@ -38,4 +37,4 @@ $ javac *.java -d build
 $ java -cp build ExerciseRunner
 Hello, How are you
 $
-```
+```