1-15-2023 Add notes to remove .txt extension if added to .java file by Windows

AprilTags-for-FTC-Blocks.md

@@ -170,6 +170,8 @@ Now the file **`AprilTagIdCode.java`** is downloaded to your computer.
 
 In OnBot Java, click the **`Upload Files`** icon.  This places the file in the **`teamcode`** folder.
 
+<i>Note: Windows might add the **".txt"** extension **without showing you**.  This file won't upload to the **`teamcode`** folder as required.  In Windows Explorer, click the **View** tab at the top, then check the box to show **File name extensions**.  Now you can see and remove the **".txt"** extension using **Rename** or the **F2 key**. Then try the upload again.</i>
+
 Still in OnBot Java (OBJ), click the filename to open it.  **Read through the Java code**, looking at the 8 methods and their myBlock annotations.  Each one will become a myBlock that appears in the Blocks menu, under Java Classes.
 
 Each annotation includes a short comment describing the method.  In general you'll use these methods in the order they are defined:
@@ -217,6 +219,8 @@ Follow the same steps as above, to download the Java code to your computer:
 
 In OnBot Java, click the **`Upload Files`** icon to place this file in the **`teamcode`** folder.</i>
 
+<i>Again, Windows might add the **".txt"** extension **without showing you**.  In Windows Explorer, click the **View** tab at the top, then check the box to show **File name extensions**.  Remove the **".txt"** extension using **Rename** or the **F2 key**, then upload.</i>
+
 There's no need here to study this Java code; it's highly technical and won't be edited for this exercise.  The program collects a camera image using OpenCV, searches it for one or more AprilTags, and draws a colorful box projecting from each AprilTag.  This pipeline can also provide location and orientation data, but we focus here on simply getting an AprilTag ID code.
 
 <p align="right"><i>[[Return to Top|https://github.com/FIRST-Tech-Challenge/FtcRobotController/wiki/AprilTags-for-FTC-Blocks]]</i><p>