spelling: restrictions

Signed-off-by: Josh Soref <[email protected]>

Author: jsoref

python/ql/lib/design.md

@@ -18,7 +18,7 @@ The analysis is built up in layers. the stack looks like this:
 Given the many interacting layers, it is important to decide which predicates are allowed to be mutually recursive in order to avoid non-monotonic recursion when negation is used to express the predicates.
 As an example, we have defined local source as those whcih do not receive local flow. This means that the local flow relation is not allowed to be recursive with anything depending on local sources.
 
-Some particular reatrictions to keep in mind:
+Some particular restrictions to keep in mind:
 
 - Typetracking needs to use a local flow step not including summaries
 - Typetracking needs to use a call graph not including summaries