Updated contrib_doc.rst

Signed-off-by: Alok Kumar <alokkumarjipura9973@gmail.com>

Author: alok1304

docs/source/contributing/contrib_doc.rst

@@ -243,7 +243,7 @@ For more information, refer this tutorial named
 .. _doc_style_conv:
 
 Style Conventions for the Documentation
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+---------------------------------------
 
 1. Headings