chore: Add README and licenses to streaming assets

Assets/StreamingAssets/Sounds/LICENSE.txt

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+# License
+The following files are licensed under [CC BY-SA 2.0](https://creativecommons.org/licenses/by-sa/2.0/) © kotoho7
+
+- jp/
+  - eew0.ogg
+  - eew3.ogg
+  - eew5.ogg
+  - eewC.ogg
+  - koushin.ogg
+  - koushinE.ogg
+
+The following files are licensed under [CC BY-SA 2.0](https://creativecommons.org/licenses/by-sa/2.0/) © kotoho7, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/) © OtoLogic
+
+- jp/
+  - VTSE5.ogg
+  - VXSE5C.ogg
+  - VXSE51.ogg
+  - VXSE52.ogg
+  - VXSE53.ogg
+  
+The following files are licensed under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/) © OtoLogic
+
+- jp/
+  - Emergency_Alert01-1-C.ogg
+  - News-Alert02-2-C.ogg
+  - News-Alert04-1-C.ogg
+
+All other files in this directory are licensed under [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/) © Cryville

Assets/StreamingAssets/Sounds/LICENSE.txt.meta

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+fileFormatVersion: 2
+guid: cce14345d934e7043b46f8c1f4174941
+DefaultImporter:
+  externalObjects: {}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: