corrected file name of prepare script in documentation
corrected file name of prepare script in documentation

Testing Done:
Copy and paste with new file name yields no error

Reviewed at https://rbcommons.com/s/twitter/r/4009/

pantsbuild/intellij-pants-plugin,pantsbuild/intellij-pants-plugin,wisechengyi/intellij-pants-plugin,pantsbuild/intellij-pants-plugin,wisechengyi/intellij-pants-plugin,wisechengyi/intellij-pants-plugin,wisechengyi/intellij-pants-plugin,pantsbuild/intellij-pants-plugin,pantsbuild/intellij-pants-plugin