Mauro's proposal changes

[SuperMauro1966]

web/language-tools-and-standard-library/basics/modules.md

In the example, there is not an indication of the execution.

Inserted the execution and some ending remarks.

----- ISSUE: #51

web/language-tools-and-standard-library/basics/data_structures

----- ISSUE: #50

web/language-tools-and-standard-library/standard-library-api/string_utils.html#valueToPrettyString

added initial section

Inclusion file:

include "string_utils.iol" from string_utils import StringUtils

I think this section could be inserted in all standard-library files, to indicate clearly the need to include/import the name of the file.

----- ISSUE: #49

web/language-tools-and-standard-library/basics/constants.md

Inserted section Comments. I suggest renaming the file in Constants-Comments

----- ISSUE: #47

web/language-tools-and-standard-library/basics/data_structures.md

inserted at the end of file a new paragraph "Beware of ->"

----- ISSUE: #46

web/language-tools-and-standard-library/basics/data_structures.md

inserted paragraph using literals

----- ISSUE: #46

web/language-tools-and-standard-library/basics/interfaces/data_types.md

----- ISSUE: #44

web/language-tools-and-standard-library/basics/interfaces/data_types.md

Inserted paragraph "String format"

----- ISSUE: #41 web/language-tools-and-standard-library/web-applications/leonardo.md

The previous code for length was incomplete. Changed the code to be complete

I'm going to close the issues associated with this pull request.