Add a description of Tuple types to Cairo document

[0xNezha]

The section of tuple types is a work in progress, so I add a description of tuple types, contribute to Cairo documentation.

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This change is 

[spapinistarkware]

Reviewable status: 0 of 1 files reviewed, 1 unresolved discussion (waiting on @0xNezha)

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docs/reference/src/components/cairo/modules/language_constructs/pages/tuple-types.adoc line 1 at r1 (raw file):

= Tuple types

Keep lines under 10-0 cahrs and end the file with a newline

[spapinistarkware]

Reviewable status: 0 of 1 files reviewed, 1 unresolved discussion (waiting on @0xNezha)

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docs/reference/src/components/cairo/modules/language_constructs/pages/tuple-types.adoc line 1 at r1 (raw file):

Previously, spapinistarkware (Shahar Papini) wrote…

Keep lines under 10-0 cahrs and end the file with a newline

under 100 chars*

[spapinistarkware]

Reviewable status: 0 of 1 files reviewed, 2 unresolved discussions (waiting on @0xNezha)

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docs/reference/src/components/cairo/modules/language_constructs/pages/tuple-types.adoc line 3 at r1 (raw file):

= Tuple types

_tuple type_ is a general way of grouping together a number of values with a variety of types into one compound type.

You don't actually describe the type fo a tuple. This is more of a description of the tuple expression.