chore: regenerate README (#416)

This PR was generated using Autosynth. 🌈


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

```
2021-03-15 14:34:30,661 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-secretmanager/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-03-15 14:34:31,515 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/3a208fd8-10c2-4134-bced-b1960f84ed38/targets

- [ ] To automatically regenerate this PR, check this box.

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-secretmanager.git",
-        "sha": "245ec0d4dd18d7f02f9bef6226f59eae7d324044"
+        "sha": "2a168f7c7d81b53d2ff138780a83177a8b61a9ac"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "2e7bd5cc66a3f0b90ce1c150eb35c89eeb9872d6"
+        "sha": "ac8f20f12e7a4c0b0ae1c6fa415f684a25ea82b7"
       }
     }
   ]

README.md

@@ -52,12 +52,12 @@ compile 'com.google.cloud:google-cloud-secretmanager'
 ```
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-secretmanager:1.4.0'
+compile 'com.google.cloud:google-cloud-secretmanager:1.4.1'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-secretmanager" % "1.4.0"
+libraryDependencies += "com.google.cloud" % "google-cloud-secretmanager" % "1.4.1"
 ```
 
 ## Authentication