Add initial community endpoint (#1145)

Author: JFWooten4

docs/data/horizon/horizon-providers.mdx

@@ -27,7 +27,13 @@ These providers allow access to the Testnet and Mainnet networks.
 
 †_Please note that Blockdaemon and Validation Cloud provide full historical data for Horizon._
 
-## SDF Provided Horizon (Futurenet and Testnet) {#sdf-provided-horizon}
+## Publicly Accessible Horizon URLs
+
+| Provider | Mainnet Endpoint | Testnet Endpoint |
+| -------- | ---------------- | ---------------- |
+| [LOBSTR](https://lobstr.co) | `https://horizon.stellar.lobstr.co` | N/A |
+
+## SDF Provided Horizon (Futurenet and Testnet only) {#sdf-provided-horizon}
 
 SDF provides a Horizon endpoint but it is rate-limited and subject to changes such as truncation of history. Developers are encouraged to select an ecosystem provider. In some cases, projects may choose to run their own Horizon instance.