Update relative links to Linux docs

This is a followup to [1].

[1] https://chromium-review.googlesource.com/c/chromium/src/+/1974901

TBR=sky

Change-Id: I442ffe121378607bdc5e1b16c081b8d66b138955
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1980900
Reviewed-by: Thomas Anderson <[email protected]>
Commit-Queue: Thomas Anderson <[email protected]>
Cr-Commit-Position: refs/heads/master@{#727226}
diff --git a/docs/linux/cast_build_instructions.md b/docs/linux/cast_build_instructions.md
index bdb8df7..4599356 100644
--- a/docs/linux/cast_build_instructions.md
+++ b/docs/linux/cast_build_instructions.md
@@ -121,7 +121,7 @@
 ### <a name="faster-builds"></a>Faster builds
 
 You might try some of the suggestions on the
-[Linux build setup](linux_build_instructions.md#faster-builds).
+[Linux build setup](build_instructions.md#faster-builds).
 
 ## Build cast\_shell
 
@@ -164,4 +164,4 @@
 ### More links
 
 *   Want to use Eclipse as your IDE? See
-    [LinuxEclipseDev](linux_eclipse_dev.md).
+    [LinuxEclipseDev](eclipse_dev.md).