chore: regenerate README (#352)

This PR was generated using Autosynth. 🌈


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

```
2020-11-10 17:36:26,406 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-speech/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-11-10 17:36:27,501 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/ebad04ba-6916-4dc2-bb71-5feb51369716/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-speech.git",
-        "sha": "2a093b2f914138fa9e14a42536d96de9fb58c654"
+        "sha": "dcde51fa70e79673ace91b658d410ebc68e49108"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "ba9918cd22874245b55734f57470c719b577e591"
+        "sha": "7db8a6c5ffb12a6e4c2f799c18f00f7f3d60e279"
       }
     }
   ]

README.md

@@ -17,7 +17,7 @@ If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>libraries-bom</artifactId>
-      <version>14.4.1</version>
+      <version>15.0.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>