Adding documentation about double quote implementation (#723)

Signed-off-by: mitchellg <mitchellg@bitquilltech.com>
Co-authored-by: Yury Fridlyand <yuryf@bitquilltech.com>

docs/user/general/datatypes.rst

@@ -353,16 +353,15 @@ A string can also represent and be converted to date and time types (except to i
 String Data Types
 =================
 
-A string is a sequence of characters enclosed in either single or double quotes. For example, both 'text' and "text" will be treated as string literal. To use quote characters in a string literal, you can include double quotes within single quoted string or single quotes within double quoted string::
+A string is a sequence of characters enclosed in either single or double quotes. For example, both 'text' and "text" will be treated as string literal. To use quote characters in a string literal, you can use two quotes of the same type as the enclosing quotes::
 
-    os> SELECT 'hello', "world", '"hello"', "'world'"
+    os> SELECT 'hello', "world", '"hello"', "'world'", '''hello''', """world"""
     fetched rows / total rows = 1/1
-    +-----------+-----------+-------------+-------------+
-    | 'hello'   | "world"   | '"hello"'   | "'world'"   |
-    |-----------+-----------+-------------+-------------|
-    | hello     | world     | "hello"     | 'world'     |
-    +-----------+-----------+-------------+-------------+
-
+    +-----------+-----------+-------------+-------------+---------------+---------------+
+    | 'hello'   | "world"   | '"hello"'   | "'world'"   | '''hello'''   | """world"""   |
+    |-----------+-----------+-------------+-------------+---------------+---------------|
+    | hello     | world     | "hello"     | 'world'     | 'hello'       | "world"       |
+    +-----------+-----------+-------------+-------------+---------------+---------------+
 
 Boolean Data Types
 ==================