Updated Backups (markdown)

Backups.md

@@ -18,7 +18,7 @@ Example: ``TWNK-KDEY-MTWT-EVGS-DRDB-KVTW``
 ## Design decisions
 
 * Using only upper case letters, no lower case letters and no numbers
-  * Using mixed upper and lower case makes it much more difficult to recall the characters from short term memory. Consider someone reading them aloud, it is required to say for every letter if it's upper or lower case. Memorizing things in short term memory works similar to reading something aloud, which makes the mixed upper/lower case backup codes double as difficult to remember than only one case backup codes.
+  * Using mixed upper and lower case makes it much more difficult to recall the characters from short term memory. Consider someone reading them aloud, it is required to say for every letter if it's upper or lower case. Memorizing things in short term memory works similar to reading something aloud, which makes the mixed upper/lower case backup codes double as difficult to remember than upper-case-only backup codes.
   * Numbers would increase the alphabet by only 10 characters, the length of the backup code would be only 2 characters shorter to achieve the same security.
   * If numbers would be included, we should use lowercase to allow better differentiation between lower and upper case. Because we don't include them we could stay with uppercase letters.
   * They look like serial numbers, like they were used for Windows, when using upper case only. Many people know serial numbers and are thus comfortable with using these.