issue 1788 slice 5: docs + Dependabot #1777 disposition + solr.version bump PR closure #2000

Parent

Part of #1788. Last slice — ships docs and closes the Dependabot-only path after real upgrade work lands.

Goal

1. Operator / release notes for SolrJ 10 (and supported Solr server matrix if product requires 10 for extract).
2. Dispose Dependabot build(deps): bump org.apache.solr:solr-solrj from 9.10.1 to 10.0.0 #1777 correctly (close as superseded/blocked once real PR exists; @dependabot ignore this major version only after intentional upgrade path is in place).
3. Ensure the real solr.version 10.x bump lives on a PR that includes slices 2–4 work — never merge version-only build(deps): bump org.apache.solr:solr-solrj from 9.10.1 to 10.0.0 #1777.

Scope

1. Docs:
   • Minimum Solr server version for new installs if we require 10
   • Upgrade path from Solr 9.x clients/servers
   • Tika Server requirement for /update/extract on Solr 10
   • Cloud vs standalone product policy (ZK still excluded today)
2. Dependabot build(deps): bump org.apache.solr:solr-solrj from 9.10.1 to 10.0.0 #1777:
   • Comment: blocked on chore(deps): upgrade Apache Solr / SolrJ from 9.10.1 to 10.x (needs code refactor) #1788 / real upgrade PR; do not merge bare bump
   • Close as superseded when slice 2 (+3/4) PR merges (or earlier if policy is “close open, track only via chore(deps): upgrade Apache Solr / SolrJ from 9.10.1 to 10.x (needs code refactor) #1788”)
   • Prefer @dependabot ignore this major version only after intentional 10.x lands or human decides to stay on 9.x temporarily
3. Parent chore(deps): upgrade Apache Solr / SolrJ from 9.10.1 to 10.x (needs code refactor) #1788 acceptance checklist tick-off when children complete.

Out of scope

• Implementing the full client refactor here if slice 2 not done
• Java 8 line

Acceptance

• Docs/release notes for operators
• build(deps): bump org.apache.solr:solr-solrj from 9.10.1 to 10.0.0 #1777 closed or clearly blocked with comment linking the real upgrade PR
• chore(deps): upgrade Apache Solr / SolrJ from 9.10.1 to 10.x (needs code refactor) #1788 acceptance criteria reviewed and closed when children done
• No bare version-only merge

Sequencing

Last. Blocked on slices 2–4 for final close; blocking comment on #1777 may be posted immediately (parent plan).