docs: improve info.description clarity in session-insights.yaml

[mohdfarhanakram]

What type of PR is this?

correction

What this PR does / why we need it:

Improves the info.description and inline descriptions in session-insights.yaml to help API consumers understand the API correctly:

• Changed "network operator" to "API provider" throughout (aligns with CAMARA terminology)
• Changed "existing Application Profile" to "selected Application Profile" (obtained via GET application-profiles)
• Removed unexpanded abbreviations: expanded RCA to "root cause analysis", WMM to "Wi-Fi Multimedia (WMM)"
• Standardized "KPI metrics" to "KPIs" for consistency
• Added "Session Identifiers" section clarifying the relationship between sessionId, id, and applicationSessionId
• Added "Object Relationships" section describing cardinality (device → sessions, application → profiles)
• Expanded the Authorization and Authentication section to explain how the device is linked to the API call via access token type
• Expanded the error code section with common CAMARA error patterns and clearer guidance
• Fixed leftover "QoS session" references to "Session Insights session" in RetrieveSessionsInput/Output

Which issue(s) this PR fixes:

Fixes #68

Special notes for reviewers:

Documentation and description changes only — no structural or functional changes to the API. All updates follow the changes listed in the issue.

Changelog input

Improved API descriptions for clarity: standardized terminology, expanded abbreviations, documented session identifiers and object relationships, and expanded authorization and error sections.

Additional documentation

N/A

[Kevsy]

Thanks @mohdfarhanakram , that's a really useful PR! One tiny suggestion made above, otherwise LGTM

[Kevsy]

Thanks, LGTM

[benhepworth]

thanks for the PR! Looks great - just a few very minor suggestions.

[mohdfarhanakram]

Thanks @benhepworth and @Kevsy for the review and suggestions — applied them all.

[benhepworth]

looks good now - thanks!