[Doc] Fix correct number of slashes when installing a plugin with zip file

docs/plugins/authors.asciidoc

@@ -112,7 +112,7 @@ directory in the root of the plugin should be served.
 === Testing your plugin
 
 When testing a Java plugin, it will only be auto-loaded if it is in the
-`plugins/` directory.  Use `bin/plugin install file://path/to/your/plugin`
+`plugins/` directory.  Use `bin/plugin install file:///path/to/your/plugin`
 to install your plugin for testing.
 
 You may also load your plugin within the test framework for integration tests.

docs/plugins/plugin-script.asciidoc

@@ -101,7 +101,7 @@ For instance, to install a plugin from your local file system, you could run:
 
 [source,shell]
 -----------------------------------
-sudo bin/plugin install file:/path/to/plugin.zip
+sudo bin/plugin install file:///path/to/plugin.zip
 -----------------------------------
 
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