What this PR does / why we need it:

Map types were added in PR #5772 but documentation only mentioned them briefly in one sentence. This PR provides comprehensive type system documentation with tables and working examples.

Added type reference tables:

• Primitive types (Int32, Int64, Float32, Float64, String, Bytes, Bool, UnixTimestamp)
• Array types (all list variants)
• Map types (Map, Array(Map)) with key/value constraints

Complete feature view example:

from feast import Entity, FeatureView, Field, FileSource
from feast.types import Int32, Float64, String, Array, Map

user_features = FeatureView(
    name="user_features",
    entities=[user],
    schema=[
        # All primitive types demonstrated
        Field(name="age", dtype=Int32),
        Field(name="credit_score", dtype=Float64),
        
        # Array types
        Field(name="daily_steps", dtype=Array(Int32)),
        
        # Map types
        Field(name="user_preferences", dtype=Map),
        Field(name="activity_log", dtype=Array(Map)),
    ],
    source=user_features_source,
)

Map usage examples:

• Simple maps: {"theme": "dark", "font_size": 14}
• Nested maps: {"profile": {"bio": "...", "location": "..."}}
• Lists of maps: [{"action": "login", "timestamp": "..."}, ...]

Which issue(s) this PR fixes:

Related to #5772 (Map type support implementation)

Misc

Documentation-only change. No code modifications.

---

This section details on the original issue you should resolve

<issue_title>feat: Support for Map value data type</issue_title>
<issue_description>Is your feature request related to a problem? Please describe.
Want to support map typed feature value in offline and online feature store.

Describe the solution you'd like
Since dict can be mapped to map type, then could be supported through feast

Describe alternatives you've considered
We have tried to flatten map into new feature view but is wasteful for feature view with lots of map type features
</issue_description>

<agent_instructions>Based on #5772 we need to update the docs on the type system supported docs/reference/type-system.md

probably would make sense to make a table with the supported types and a single feature view with all of the listed types as an example that can be copy pasted.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@franciscojavierarceo @nquinn408 I see you have a fork with some of these already supported? I think we technically already support dictionary types but maybe it's not documented or maybe under only some conditions?

• Fixes feat: Support for Map value data type #5768

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