index.org: Mention Orga and Pandoc in the tool page

* index.org (Org-mode parsers): add link to homepage and brief description for
Orga, an ES parsers for org, and Pandoc, the multi-purpose converter.

TINYCHANGE

org-tools/index.org

@@ -111,6 +111,17 @@ org-js is a javascript parser and converter for org-mode
 For a working example of an interactive editor, see
 http://mooz.github.com/org-js/editor/.
 
+** [[https://github.com//xiaoxinghu/orgajs][orga]] by Xiaoxing Hu
+
+Orga is a flexible Org syntax parser. It parses Org content into AST
+(Abstract Syntax Tree).
+
+** [[https://pandoc.org][pandoc]]
+
+Pandoc is the Swiss-army knife to convert files from one markup format
+into another, it can convert documents from many source format,
+including Org, to many other.
+
 * Specific purpose tools
 
 ** orgmode for drupal