Fix typo in link to ccache for Mac

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Review URL: https://codereview.chromium.org/1624903002

Cr-Commit-Position: refs/heads/master@{#371150}
diff --git a/docs/mac_build_instructions.md b/docs/mac_build_instructions.md
index 10c9e5d..6a35330 100644
--- a/docs/mac_build_instructions.md
+++ b/docs/mac_build_instructions.md
@@ -82,7 +82,7 @@
 to disable debug symbols altogether, this makes both full rebuilds and linking
 faster (at the cost of not getting symbolized backtraces in gdb).
 
-You might also want to [install ccache](ccache_cac.md) to speed up the build.
+You might also want to [install ccache](ccache_mac.md) to speed up the build.
 
 ## Running