Fixing two more bad links (#12)

com.unity.perception/Documentation~/Schema/Synthetic_Dataset_Schema.md

 
 ##### semantic segmentation - grayscale image
 
-A grayscale PNG file that stores integer values (label pixel_value in [annotation spec](#annotation_definitions) reference table, semantic segmentation) of the labeled object at each pixel. 
+A grayscale PNG file that stores integer values (label pixel_value in [annotation spec](#annotation_definitionsjson) reference table, semantic segmentation) of the labeled object at each pixel. 
 
 ![image alt text](image_2.png)
 
 A json file that stores collections of metric specifications records (metric_definition). 
 Each specification record describes a particular metric stored in [metrics](#metrics) values. 
 Each metric_definition record is assigned a unique identifier to a collection of specification records, which is stored as a list of key-value pairs. 
-The design is very similar to [annotation_definitions](#annotation_definitions.json).
+The design is very similar to [annotation_definitions](#annotation_definitionsjson).
 
 ```
 metric_definition {