docs: fix README feature list and RefreshCookieName comment

[veverkap]

• Add 'generic OAuth2 login (GitHub, Discord, Slack, and any custom provider)' to the intro feature list; the OAuth2Handler and built-in providers (GitHubProvider, GoogleOAuth2Provider) exist in the codebase but were absent from the README description (present in docs/index.md)
• Correct the RefreshCookieName quick-start comment from 'optional' to 'required when Sessions is set'; AuthHandler.Validate() enforces this constraint and returns an error when Sessions is non-nil but RefreshCookieName is empty

Greptile Summary

This PR makes two documentation-only corrections to README.md: it adds generic OAuth2 login to the intro feature list (matching the existing OAuth2Handler and built-in providers already present in the codebase), and updates the RefreshCookieName quick-start comment from "optional" to "required when Sessions is set" (matching AuthHandler.Validate() enforcement and the auth.go struct comment).

• The OAuth2 addition accurately reflects handler/oauth2.go and the built-in GitHubProvider/GoogleOAuth2Provider implementations.
• The RefreshCookieName correction aligns the quick-start comment with actual runtime behaviour, but the equivalent comment in the detailed AuthHandler reference block (line 520) still reads // optional and was not updated in this PR.

Confidence Score: 4/5

Safe to merge — documentation-only change with no runtime impact.

Both changes are accurate relative to the source code. The only remaining gap is a parallel "optional" label for RefreshCookieName in the detailed AuthHandler reference block that this PR did not touch, leaving the README internally inconsistent on that point.

README.md line 520 — the detailed AuthHandler struct example still labels RefreshCookieName as optional.

Important Files Changed

Filename	Overview
README.md	Two doc-only changes: adds generic OAuth2 to the intro feature list (accurate, matching handler/oauth2.go), and corrects the RefreshCookieName quick-start comment from "optional" to "required when Sessions is set" (matches AuthHandler.Validate() enforcement). A parallel occurrence of the old "optional" label remains in the detailed AuthHandler reference block at line 520.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[AuthHandler configured] --> B{Sessions set?}
    B -- No --> C[RefreshCookieName optional\nRefresh tokens disabled]
    B -- Yes --> D{RefreshCookieName set?}
    D -- No --> E[Validate returns error\ntoken issuance HTTP 500]
    D -- Yes --> F[Refresh token issued\nstored in HttpOnly cookie]

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Comments Outside Diff (1)

1. README.md, line 520 (link)

   The RefreshCookieName field is still labelled // optional in the detailed AuthHandler reference block further down in the README. This is now inconsistent with the quick-start comment fixed in this PR and with the auth.go source comment ("Required when Sessions is non-nil"). AuthHandler.Validate() returns an error when Sessions is set and RefreshCookieName is empty, so calling it optional is misleading.

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: README.md
   Line: 520
   
   Comment:
   The `RefreshCookieName` field is still labelled `// optional` in the detailed `AuthHandler` reference block further down in the README. This is now inconsistent with the quick-start comment fixed in this PR and with the `auth.go` source comment ("Required when Sessions is non-nil"). `AuthHandler.Validate()` returns an error when `Sessions` is set and `RefreshCookieName` is empty, so calling it optional is misleading.
   
   
   
   How can I resolve this? If you propose a fix, please make it concise.

   

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
README.md:520
The `RefreshCookieName` field is still labelled `// optional` in the detailed `AuthHandler` reference block further down in the README. This is now inconsistent with the quick-start comment fixed in this PR and with the `auth.go` source comment ("Required when Sessions is non-nil"). `AuthHandler.Validate()` returns an error when `Sessions` is set and `RefreshCookieName` is empty, so calling it optional is misleading.

```suggestion
    RefreshCookieName: "refresh",  // required when Sessions is set; stores refresh token in an HttpOnly cookie
```

_{Reviews (1): Last reviewed commit: "docs: fix README feature list and Refres..." | Re-trigger Greptile}

[Copilot]

Pull request overview

Updates top-level documentation to accurately reflect existing OAuth2 support and handler configuration requirements.

Changes:

• Add generic OAuth2 login (e.g., GitHub/Discord/Slack/custom providers) to the README feature list to match the existing OAuth2Handler functionality documented elsewhere.
• Correct the Quick Start RefreshCookieName comment to indicate it’s required when Sessions is set (consistent with AuthHandler.Validate() behavior).

Show a summary per file

File	Description
README.md	Aligns the feature list with existing OAuth2 capabilities and fixes Quick Start guidance for RefreshCookieName when Sessions is enabled.

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• Files reviewed: 1/1 changed files
• Comments generated: 0