Adding documentation about double quote implementation

[MitchellGale]

Description

Adds documentation to datatypes.rst regarding implementation and functionality for double quotes being used as escape characters in some situations. See below table for example of implementation. See https://dev.mysql.com/doc/refman/8.0/en/string-literals.html mysql documentation.

+-----------+-----------+-------------+-------------+---------------+---------------+
| 'hello'   | "world"   | '"hello"'   | "'world'"   | '''hello'''   | """world"""   |
|-----------+-----------+-------------+-------------+---------------+---------------|
| hello     | world     | "hello"     | 'world'     | 'hello'       | "world"       |
+-----------+-----------+-------------+-------------+---------------+---------------+

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov-commenter]

Codecov Report

Merging #723 (061dd67) into main (1df89e3) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main     #723   +/-   ##
=========================================
  Coverage     97.76%   97.76%           
  Complexity     2880     2880           
=========================================
  Files           276      276           
  Lines          7077     7077           
  Branches        447      447           
=========================================
  Hits           6919     6919           
  Misses          157      157           
  Partials          1        1           

Flag	Coverage Δ
sql-engine	97.76% <ø> (ø)

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[dai-chen]

Thanks for the changes!

[penghuo]

CI failed?
Could you merge the commits in case there is only one file change?

[joshuali925]

I'll merge in, CI failing should be irrelevant to this PR