modified readme

description enhanced

README.md

@@ -5,5 +5,5 @@ Python Script for exporting zotero feeds to OPML.
 ## Usage
 
 1. Run script, for example, `python3 zotero-export-opml.py`
-2. Find `zotero.sqlite`. You can refer to https://www.zotero.org/support/zotero_data.
+2. Input file path of `zotero.sqlite`. You can refer to https://www.zotero.org/support/zotero_data.
 3. Now you get `zotero_feeds.opml`.
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