info on custom functions

README.md

@@ -18,7 +18,8 @@ Download the most recent [Release from Github](https://github.com/demisjohn/Micr
 
 View the [Instructions PDF on Github](https://github.com/demisjohn/Microscope-Measurement-Tools/blob/master/Microscope%20Meas.%20-%20Calibration%20instructions.pdf) for the Installation & Calibration procedure.
 
-Three files are included:
+## Usage
+Three files are included, which will show up in your FIJI "Analyze" menu:
 
 + **Choose_Microscope_Calibration.py**
   + *Opens the "Choose Calibration" window, for setting the measurement scale to a preconfigured value.*
@@ -27,11 +28,15 @@ Three files are included:
 + **Microscope_Calibrations_user_settings.py**
   + *User-editable Settings file that contains your pre-configured scale calibrations, along with settings for drawing annotations (background/text color etc.)*
   + Please see the Instructions PDF for detailed instructions on setting up your settings file with Calibrations.
-
-
+
 [MMT-Choose-Cal-Pic]: http://fiji.sc/_images/c/cd/Microscope_Meas_Tools_-_Choose_Calibration_01.png
 [MMT-Annot-Line-Pic]: http://fiji.sc/_images/f/f4/Microscope_Meas_Tools_-_Draw_Meas_Line.png
 
+### Custom Calibration Functions
+A custom function can be added to the list of available calibrations.  A sub-folder is included showing an example of how to do this. The example is for a JEOL SEM, and the function will load an accompanying text file to determine the scale of the SEM image.
+
+See the files in the sub-folder "*MScopeCals - custom function example*" for more info.
+
 ## Contact
 
 Feel free to add Issues/feature requests, or even better, Fork the `git` repository and submit your own updates (see this [how-to](http://kbroman.org/github_tutorial/pages/fork.html))!