updated specification.rst file link

Author: Naveen-singla

README.rst

@@ -21,8 +21,7 @@ identify redistributable source code used in your project to help you comply
 with open source licenses conditions.
 
 This version of the AboutCode Toolkit follows the ABOUT specification version 3.2.1 at:
-https://github.com/nexB/aboutcode-toolkit/blob/develop/SPECIFICATION.rst
-
+https://github.com/nexB/aboutcode-toolkit/blob/develop/docs/source/specification.rst
 
 Build and tests status
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