chore: regenerate README (#844)

This PR was generated using Autosynth. 🌈


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

```
2021-08-12 02:16:28,310 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-asset/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-08-12 02:16:29,613 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/7a82d18b-dd7c-4605-93df-fc5849b23e79/targets

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-asset.git",
-        "sha": "2ec566a3bd3677190af389f02fc96e9c1c8cb97f"
+        "sha": "84e9747db1ea647a7432751e4c1c20a14484c984"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "82fe6d92bf9cf8a042a33234aa02343f73c12492"
+        "sha": "7e1f6da50524b5d98eb67adbf6dd0805df54233d"
       }
     }
   ]

README.md

@@ -57,13 +57,13 @@ compile 'com.google.cloud:google-cloud-asset'
 If you are using Gradle without BOM, add this to your dependencies
 
 ```Groovy
-compile 'com.google.cloud:google-cloud-asset:2.6.0'
+compile 'com.google.cloud:google-cloud-asset:3.0.0'
 ```
 
 If you are using SBT, add this to your dependencies
 
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-asset" % "2.6.0"
+libraryDependencies += "com.google.cloud" % "google-cloud-asset" % "3.0.0"
 ```
 
 ## Authentication