Merge pull request #169 from gwbres/readme

readme: fix BeiDou typo

README.md

@@ -37,7 +37,7 @@ This library is validated against NASA/NAIF SPICE for the Ephemeris Time to Univ
 + Dynamic Barycentric Time (TDB), a higher fidelity ephemeris time
 + Global Positioning System (GPST)
 + Galileo System Time (GST)
-+ BaiDou Time (BDT)
++ BeiDou Time (BDT)
 + UNIX
 ## Non-features
 * Time-agnostic / date-only epochs. Hifitime only supports the combination of date and time, but the `Epoch::{at_midnight, at_noon}` is provided as a helper function.
@@ -341,4 +341,4 @@ In order to provide full interoperability with NAIF, hifitime uses the NAIF algo
 ## 2.2.3
 + More deterministic `as_jde_tdb_days()` in `Epoch`. In version 2.2.1, the ephemeris time and TDB _days_ were identical down to machine precision. After a number of validation cases in the rotation equations of the IAU Earth to Earth Mean Equator J2000 frame, the new formulation was shown to lead to less rounding errors when requesting the days. These rounding errors prevented otherwise trivial test cases. However, it adds an error of **40.2 nanoseconds** when initializing an Epoch with the days in ET and requesting the TDB days.
 
-_Note:_ this was originally published as 2.2.2 but I'd forgotten to update one of the tests with the 40.2 ns error.
+_Note:_ this was originally published as 2.2.2 but I'd forgotten to update one of the tests with the 40.2 ns error.