According to the documentation (read it here) the manifest file of a component must be named manifest.xml or <extension_name>.xml.

However if you use the name manifest.xml the component will install properly, but fail to work. Probably you'll get errors lile 'Class ... not found' or 'Layout default not found'. It took me ages to figure out if i made some typo somewhere, but it turns out that the manual and documentation is wrong:

The following line in the code expects the manifext to be called <extension_name>.xml and that you component declares it namespace tag in the manifest, otherwise it will not generate an entry in the namespace map and you'll end up wasting time.

Either update the doc, or add a line for manifest.xml to the code.