libstfinv [WP][DOC]: remove bullets (might be mistaken for a minus)

src/libs/libstfinv/usage/stfinvfourier_description_usage.txt

@@ -45,9 +45,9 @@ internally. Time value are allowed to be negative. Prior to application of the
 correction filter to the time series passed to the algorithm, the correction
 filter is transformed to the time domain, tapered, and then transformed to the
 Fourier domain again. The values of the taper are:
-  - 0                              if       t <  t1
-  - 0.5-0.5*cos(pi*(t-t1)/(t2-t1)) if t1 <= t <= t2
-  - 1                              if t2 <  t <  t3
-  - 0.5+0.5*cos(pi*(t-t3)/(t3-t4)) if t3 <= t <= t4
-  - 0                              if       t >  t4
+  0                              if       t <  t1
+  0.5-0.5*cos(pi*(t-t1)/(t2-t1)) if t1 <= t <= t2
+  1                              if t2 <  t <  t3
+  0.5+0.5*cos(pi*(t-t3)/(t3-t4)) if t3 <= t <= t4
+  0                              if       t >  t4
 # ----- END OF stfinvfourier_description_usage.txt -----