add missing subgraph results (apollographql#2171)

docs/source/supported-subgraphs.md

@@ -135,6 +135,7 @@ The following open-source GraphQL server libraries and hosted solutions support
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 <tr><td><a href="https://ghostdogpr.github.io/caliban/docs/federation.html">Caliban</a></td><td><table><tr><th>_service</th><td>🟢</td></tr><tr><th>@key (single)</th><td>🟢</td></tr><tr><th>@key (multi)</th><td>🟢</td></tr><tr><th>@key (composite)</th><td>🟢</td></tr><tr><th>repeatable @key</th><td>🟢</td></tr><tr><th>@requires</th><td>🟢</td></tr><tr><th>@provides</th><td>🟢</td></tr><tr><th>federated tracing</th><td>🟢</td></tr></table></td><td><table><tr><th>@link</th><td>🟢</td></tr><tr><th>@shareable</th><td>🟢</td></tr><tr><th>@tag</th><td>🟢</td></tr><tr><th>@override</th><td>🟢</td></tr><tr><th>@inaccessible</th><td>🟢</td></tr></table></td></tr>
+<tr><td><a href="https://sangria-graphql.github.io/learn/#graphql-federation">Sangria</a></td><td><table><tr><th>_service</th><td>🟢</td></tr><tr><th>@key (single)</th><td>🟢</td></tr><tr><th>@key (multi)</th><td>🟢</td></tr><tr><th>@key (composite)</th><td>🟢</td></tr><tr><th>repeatable @key</th><td>🟢</td></tr><tr><th>@requires</th><td>🟢</td></tr><tr><th>@provides</th><td>🟢</td></tr><tr><th>federated tracing</th><td>🟢</td></tr></table></td><td><table><tr><th>@link</th><td>❌</td></tr><tr><th>@shareable</th><td>🟢</td></tr><tr><th>@tag</th><td>🟢</td></tr><tr><th>@override</th><td>🟢</td></tr><tr><th>@inaccessible</th><td>🟢</td></tr></table></td></tr>
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