Merge #16626: doc: Fix spelling error chache -> cache.

f9d40ce7eb Fix spelling error chache -> cache. (Nils Loewen)

Pull request description:

  Fixes a spelling error in `.travis.yml`.

ACKs for top commit:
  fanquake:
    ACK f9d40ce7eb

Tree-SHA512: f38542f4e1225f2670aeb8f663440f843aa5cdd4588313a88bdfb36531c3419112b55775f12368b80ebd3e0fa5b5491ae43b18ccab39b7908f98bc6b6c7ca396

.travis.yml

@@ -17,7 +17,7 @@
 # Bitcoin Core GitHub member via the Travis web interface [0].
 #
 # Travis CI uploads the cache after the script phase of the build [1].
-# However, the build is terminated without saving the chache if it takes over
+# However, the build is terminated without saving the cache if it takes over
 # 50 minutes [2]. Thus, if we spent too much time in early build stages, fail
 # with an error and save the cache.
 #