format mistake fixed

docs/libcurl/curl_easy_setopt.3

@@ -485,7 +485,7 @@ Optionally, you can provide data to POST using the \fICURLOPT_READFUNCTION\fP
 and \fICURLOPT_READDATA\fP options but then you must make sure to not set
 \fICURLOPT_POSTFIELDS\fP to anything but NULL. When providing data with a
 callback, you must transmit it using chunked transfer-encoding or you must set
-the size of the data with the \fICURLOPT_POSTFIELDSIZE\f option.
+the size of the data with the \fICURLOPT_POSTFIELDSIZE\fP option.
 
 You can override the default POST Content-Type: header by setting your own
 with \fICURLOPT_HTTPHEADER\fP.