docs: clarify ETF watchlist exposure

Author: daggerok

README.md

@@ -1,6 +1,6 @@
 # WisdomTree
 
-WisdomTree ETF holdings to Watchlist. A single-file client-side tool reading the generated `./api/wisdomtree` static feed (WisdomTree product pages — including official Market Price/NAV/Underlying Index returns and the official tax-character distributions table, SEC EDGAR N-PORT-P holdings, Yahoo Finance history with a narrow distributions/returns fallback) into a searchable ETF/asset-class catalog with per-fund tabs, watchlist, N-PORT upload, CSV/TXT export — the same look, feel, columns and business logic as the sibling applications.
+One of the app's features lets you select WisdomTree ETFs in the Watchlist and aggregate their holdings to see how often each ticker appears across the selected funds. Repeated holdings make overlapping exposure visible: the more selected funds include a ticker, the greater its potential influence on the portfolio; gains in that holding may help, while declines may hurt, and actual impact also depends on each fund's position size. A single-file client-side tool reading the generated `./api/wisdomtree` static feed (WisdomTree product pages — including official Market Price/NAV/Underlying Index returns and the official tax-character distributions table, SEC EDGAR N-PORT-P holdings, Yahoo Finance history with a narrow distributions/returns fallback) into a searchable ETF/asset-class catalog with per-fund tabs, watchlist, N-PORT upload, CSV/TXT export — the same look, feel, columns and business logic as the sibling applications.
 
 ## Using Bun