Add file structure for automatic unit-testing

docs/README.md

@@ -36,6 +36,13 @@ of these commands:
     make clean
     make distclean
 
+Isolated unit tests allow you to verify all testable
+components are behaving as expected. Please note that most
+tests will be added later down the road, when the project
+has reached a more mature state.
+
+    make check
+
 You can listen on the serial debug interface by running
 the command below. This will also initialize all optional
 submodules on first invocation.
@@ -64,8 +71,8 @@ Issue the SET command to update the target settings:
 
 Settings are stored in EEPROM and are persistent until a new
 SET command is issued. Keywords are not case-sensitive. Both
-arguments may contain a decimal point followed by a sequence
-of digits.
+arguments may contain an optional decimal point followed by
+a sequence of digits.
 
 ### Webinterface Example