Merge pull request #233 from JuliaMath/JeffreySarnoff-patch-7

Fix typo in README regarding Double64 type

Author: JeffreySarnoff

README.md

@@ -3,7 +3,7 @@
 ### Math with 85+ accurate bits.
 #### Extended precision float and complex types
 
-- N.B. `Double64` is the most performant type <sup>[β](#involvement)</sup>
+- Note: `Double64` is the most performant type <sup>[β](#involvement)</sup>