chore: regenerate README (#444)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2021-04-09 19:24:20,934 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-datalabeling/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-04-09 19:24:22,209 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/e0f14d9b-d0c0-42f9-8dad-d5c9fa1c2ee5/targets

- [ ] To automatically regenerate this PR, check this box. (May take up to 24 hours.)

.github/readme/synth.metadata/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-datalabeling.git",
-        "sha": "4bd26dc4c4440930a4505a84bc978da24649744d"
+        "sha": "d327741f4be51a91bc8b9cd13624f99976a9b0cb"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "60fc32cc950c20cfdd774b846a4a7dc5d1e4d0ef"
+        "sha": "1f5e6bc8dc8e3661ee550905fc070e55e1b6cea1"
       }
     }
   ]

README.md

@@ -8,9 +8,12 @@ Java idiomatic client for [Data Labeling][product-docs].
 - [Product Documentation][product-docs]
 - [Client Library Documentation][javadocs]
 
+
 > Note: This client is a work-in-progress, and may occasionally
 > make backwards-incompatible changes.
 
+
+
 ## Quickstart
 
 If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file