chore: typo fix (#5)

Author: TomAFrench

README.md

@@ -116,7 +116,7 @@ There is an up-front processing cost, as well as a per-query cost.
 | 8kb       | 307k                               |
 | 16kb      | 574k                               |
 
-| query type | query cost (in megaplonk gaes) |
+| query type | query cost (in megaplonk gates) |
 |-|-|
 | `get_value` | 364 |
 | `get_number` | 454 |