Clarify the search precedence for .ruby-version files.

Closes #432 [ci skip]

README.md

@@ -108,13 +108,14 @@ reading it from the following sources, in this order:
    the [`rbenv shell`](#rbenv-shell) command to set this environment
    variable in your current shell session.
 
-2. The application-specific `.ruby-version` file in the current
-   directory, if present. You can modify the current directory's
-   `.ruby-version` file with the [`rbenv local`](#rbenv-local)
-   command.
-
-3. The first `.ruby-version` file found by searching each parent
-   directory until reaching the root of your filesystem, if any.
+2. The first `.ruby-version` file found by searching the directory of the
+   script you are executing and each of its parent directories until reaching
+   the root of your filesystem.
+
+3. The first `.ruby-version` file found by searching the current working
+   directory and each of its parent directories until reaching the root of your
+   filesystem. You can modify the `.ruby-version` file in the current working
+   directory with the [`rbenv local`](#rbenv-local) command.
 
 4. The global `~/.rbenv/version` file. You can modify this file using
    the [`rbenv global`](#rbenv-global) command. If the global version