Fix table format on README

Author: messense

README.rst

@@ -80,8 +80,8 @@ You can define rust extension with `RustExtension` class:
                        `Binding.RustCPython` uses rust-cpython
                        `Binding.NoBinding` uses no binding.
 
-    :param bool optional: if it is true, a build failure in the extension will not abort the build process,
-                          but instead simply not install the failing extension.
+   :param bool optional: if it is true, a build failure in the extension will not abort the build process,
+                         but instead simply not install the failing extension.
 
 Commands
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