upgrade versions and docs

[Amos-Rai-KEYS]

Bump version to 2.0.0 and expand annotation documentation

Summary

• Bump API version from 1.1.1 to 2.0.0 across api/info.yaml, artifacts/openapi.yaml, and artifacts/infragraph.proto
• Redesign the get_graph request schema: rename format to choice, insert infragraph as a new return type alongside networkx, and introduce a structured GraphResponseInfragraph response object
• Expand annotate_graph docs to cover the new links target (in addition to nodes and edges) with a consolidated code example showing all three
• Add a new Node Name Slicing section documenting the slice-notation shorthand (server[0:2]xpu[0:3]) and how it expands to fully qualified dot-separated names
• Clarify inline descriptions in existing rank and ipaddress examples to explicitly mention Annotation object and attributes.add
• Fix typo: infrastructre → infrastructure in docs/src/index.md

Breaking changes (1.1.1 → 2.0.0)

The get_graph request schema changed in PR #52 in a way that is not backward compatible:

• format field renamed to choice — any client code referencing GetGraphRequest.format must be updated to GetGraphRequest.choice
• networkx enum value shifted from 1 to 2 — a new infragraph = 1 variant was inserted before it. Clients that were passing the integer 1 to select networkx will now silently request the infragraph format instead
• New structured response type — get_graph can now return a GraphResponseInfragraph object (infrastructure + annotations) in addition to the previous networkx YAML string; clients that assume a plain YAML string response must be updated to handle the new response shape

Implementers upgrading from 1.1.1 should audit all get_graph call sites, replace format with choice, and verify the enum value passed matches the intended representation.

Annotation API — restructured schema

The Annotation object was fully redesigned. The old flat nodes.add(id, name, value) pattern no longer exists:

# 1.1.1 — no longer valid
annotation.nodes.add(id="dgx.0.xpu.0", name="rank", value="0")

# 2.0.0
node = annotation.nodes.add(name="dgx.0.xpu.0")
node.attributes.add(attribute="rank", value="0")

[ajbalogh]

Because there is a major version change, this PR summary should also include a comment describing what broke backward compatibility so that implementers can take steps to mitigate

[Amos-Rai-KEYS]

@ajbalogh I have addressed your comment.