Fix Typo

sections/intro/faster_rcnn_approach.md

@@ -2,5 +2,5 @@ For example, a FasterRCNN approach uses the following steps:
 - the image features are given out by a FPN (Feature Pyramid Net) over a ResNet backbone, and
 - then a RPN (Regision Proposal Network) layer detects proposals in those features, and
 - then the ROI (Region of Interest) heads get the box proposals in the original image, and
-- the the boxes are selected using a NMS (Non-max suppression),
+- then the boxes are selected using a NMS (Non-max suppression),
 - and then the features for selected boxes are used as visual features.