org-entities: Add \dollar and \USD

* lisp/org-entities.el (org-entities): Add \dollar and \USD.

etc/ORG-NEWS

@@ -389,6 +389,7 @@ Now ~=...=~ markup uses ~@samp{}~ instead of ~@verb{}~.  You can use
 *** Texinfo default table markup is ~@asis~
 It used to be ~@samp~ but ~@asis~ is neutral and, therefore, more
 suitable as a default value.
+*** New entities : ~\dollar~ and ~\USD~
 *** ~org-parse-time-string~ accepts a new optional argument
 =ZONE= specifies the current time zone.
 

lisp/org-entities.el

@@ -295,6 +295,8 @@ packages to be loaded, add these packages to `org-latex-packages-alist'."
      ("yen" "\\textyen{}" nil "¥" "yen" "¥" "¥")
      ("euro" "\\texteuro{}" nil "€" "EUR" "EUR" "€")
      ("EUR" "\\texteuro{}" nil "€" "EUR" "EUR" "€")
+     ("dollar" "\\$" nil "$" "$" "$" "$")
+     ("USD" "\\$" nil "$" "$" "$" "$")
 
      "** Property Marks"
      ("copy" "\\textcopyright{}" nil "©" "(c)" "©" "©")