Update anchor generation

[artberger]

So that if there are duplicate anchors on the page, they are sequentially numbered. e.g.,

1. First time: OpenAI → #openai
2. Second time: OpenAI → #openai-1
3. Third time: OpenAI → #openai-2 and so on...

Context in Slack thread: https://solo-io-corp.slack.com/archives/C0520LDVD2Q/p1758237035410509
BOT NOTES:
resolves https://github.com/solo-io/doctopus/issues/124

Tested this in the gloo repo by:

1. updating the go.mod file to point to my branch of solo-kit, by adding this replace at the end of the file: replace github.com/solo-io/solo-kit => github.com/solo-io/solo-kit v0.39.3-0.20250919152847-fa661d993ca2
2. running make go-generate-all to generate the API docs
3. checking the ai.proto.sk.md file, which as the anchors, e.g., #openai-1 in the toc below

---
title: "Ai"
weight: 5
---

<!-- Code generated by solo-kit. DO NOT EDIT. -->


### Package: `ai.options.gloo.solo.io` 
**Types:**


- [SingleAuthToken](#singleauthtoken)
- [Passthrough](#passthrough-1)
- [UpstreamSpec](#upstreamspec)
- [PathOverride](#pathoverride)
- [CustomHost](#customhost)
- [OpenAI](#openai)
- [AzureOpenAI](#azureopenai)
- [Gemini](#gemini)
- [VertexAI](#vertexai)
- [Publisher](#publisher)
- [Mistral](#mistral)
- [Anthropic](#anthropic)
- [Bedrock](#bedrock)
- [AwsCredentialProvider](#awscredentialprovider)
- [AWSInline](#awsinline)
- [MultiPool](#multipool)
- [Backend](#backend)
- [Priority](#priority)
- [RouteSettings](#routesettings)
- [RouteType](#routetype)
- [FieldDefault](#fielddefault-1)
- [Postgres](#postgres)
- [Embedding](#embedding)
- [OpenAI](#openai-1)
- [AzureOpenAI](#azureopenai-1)
- [SemanticCache](#semanticcache)
- [Redis](#redis)
- [Weaviate](#weaviate)
- [DataStore](#datastore)
- [Mode](#mode-1)
- [RAG](#rag)
- [DataStore](#datastore-1)
- [AIPromptEnrichment](#aipromptenrichment)
- [Message](#message-1)
- [AIPromptGuard](#aipromptguard)
- [Regex](#regex)
- [RegexMatch](#regexmatch)
- [BuiltIn](#builtin)
- [Action](#action-3)
- [Webhook](#webhook)
- [HeaderMatch](#headermatch)
- [MatchType](#matchtype)
- [Moderation](#moderation)
- [OpenAI](#openai-2)
- [Request](#request-1)
- [CustomResponse](#customresponse)
- [Response](#response)
  
...

[solo-changelog-bot]

Issues linked to changelog:
https://github.com/solo-io/doctopus/issues/124