[gnome-builder] docs: add section on special characters

[Christian Hergert <chergert src gnome org>]

commit 318f3d3a2a5815f551a9d58b4d8b9e0ee9313ade
Author: Christian Hergert <chergert redhat com>
Date:   Wed Sep 6 10:58:07 2017 -0700

    docs: add section on special characters

 doc/howto/search_and_replace.rst |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/doc/howto/search_and_replace.rst b/doc/howto/search_and_replace.rst
index 85192cc..29bbf87 100644
--- a/doc/howto/search_and_replace.rst
+++ b/doc/howto/search_and_replace.rst
@@ -16,3 +16,10 @@ Enter the replacement text in the second text entry.
 Select “Replace” to replace the next match or “Replace All” to replace all matches.
 
 .. _g_regex_replace: 
https://developer.gnome.org/glib/stable/glib-Perl-compatible-regular-expressions.html#g-regex-replace
+
+Using Special Characters
+========================
+
+If you want to insert or replace a tab character using "search and replace", you need to use the escaped 
form of tab (``\t``).
+You can also do this for new lines with ``\n``.
+