It may Take a lot of time instead of 2 hours

Author: spastorino

src/walkthrough.md

@@ -192,8 +192,8 @@ it.
 When your review approves the PR, it will go into a queue for yet another bot
 called `@bors`.  `@bors` manages the CI build/merge queue. When your PR reaches
 the head of the `@bors` queue, `@bors` will test out the merge by running all
-tests against your PR on Travis CI. This takes about 2 hours as of this
-writing.  If all tests pass, the PR is merged and becomes part of the next
+tests against your PR on Travis CI. This takes may take a lot of time to
+finish. If all tests pass, the PR is merged and becomes part of the next
 nightly compiler!
 
 There are a couple of things that may happen for some PRs during the review process