Update OPA.md (#446)

When running the code again, I found that the macOS chmod command in this file fails with the hashtag and text afterwards. This commit will remove the tag and comment on the command itself.

docs/installation/OPA.md

@@ -33,8 +33,9 @@ python download_opa.py -v 0.60.0 -os macos
 - Use the `scubagoggles gws --omitsudo` flag to omit running the executable with `sudo`.
 - MAC and Linux OS users should have their OPA executables named `opa_darwin_amd64` or `opa_linux_amd64_static` respectively for scubagoggles execution.
 - The OPA executable must also be given execute permissions
+- Run the following command to give the opa executable execute permissions:
 ```bash
-chmod +x opa_darwin_amd64 # give the opa executable execute permissions
+chmod +x opa_darwin_amd64
 ```
 
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