org.texi (Emphasis and monospace): Mention `org-fontify-emphasized-text' and `org-emphasis-regexp-components'

* org.texi (Emphasis and monospace): Mention
`org-fontify-emphasized-text' and
`org-emphasis-regexp-components'.

Thanks to Roland Winkler for suggesting this.

doc/org.texi

@@ -9271,11 +9271,18 @@ multiple footnotes side by side.
 @cindex verbatim text, markup rules
 @cindex code text, markup rules
 @cindex strike-through text, markup rules
+@vindex org-fontify-emphasized-text
+@vindex org-emphasis-regexp-components
 You can make words @b{*bold*}, @i{/italic/}, _underlined_, @code{=code=}
 and @code{~verbatim~}, and, if you must, @samp{+strike-through+}.  Text
 in the code and verbatim string is not processed for Org mode specific
 syntax; it is exported verbatim.
 
+To turn off fontification for marked up text, you can set
+@code{org-fontify-emphasized-text} to @code{nil}.  To fine tune what
+characters are allowed before and after the special characters, see
+@code{org-emphasis-regexp-components}.
+
 @node Horizontal rules, Comment lines, Emphasis and monospace, Structural markup elements
 @subheading  Horizontal rules
 @cindex horizontal rules, markup rules