Use correct separator in keywords.txt

The Arduino IDE requires the use of a tab separator between the name and identifier. Without this tab the keyword is not highlighted.

Reference: https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5:-Library-specification#keywords

Author: per1234

keywords.txt

@@ -6,7 +6,7 @@
 # Datatypes (KEYWORD1)
 #######################################
 
-MAX30105 KEYWORD1
+MAX30105	KEYWORD1
 
 #######################################
 # Methods and Functions (KEYWORD2)