Fix spelling mistakes in //docs.

docs/linux_sysroot.md

 # Linux sysroot images
 
 The chromium build system for Linux will (by default) use a sysroot image
 rather than building against the libraries installed on the host system.
 This serves several purposes.  Firstly, it ensures that binaries will run on all
 supported linux systems independent of the packages installed on the build
 machine.  Secondly, it makes the build more hermetic, preventing issues that
 arise for variations among developers' systems.
 
 The sysroot consists of a minimal installation of Debian/stable (or old-stable)
 to ensure maximum compatibility.  Pre-built sysroot images are stored in
 Google Cloud Storage and downloaded during `gclient runhooks`
 
 ## Installing the sysroot images
 
 Installation of the sysroot is performed by
 `build/linux/sysroot_scripts/install-sysroot.py`.
 
 This script can be run manually but is normally run as part of gclient
 hooks. When run from hooks this script in a no-op on non-linux platforms.
 
 ## Rebuilding the sysroot image
 
 The pre-built sysroot images occasionally needs to be rebuilt.  For example,
-when security updates to debian are released, or when a new package is needed by
+when security updates to Debian are released, or when a new package is needed by
 the chromium build.
 
 ### Rebuilding
 
 To rebuild the images (without any changes) run the following commands:
 
     $ cd build/linux/sysroot_scripts
     $ ./sysroot-creator-wheezy.sh BuildSysrootAll
 
 The above command will rebuild the sysroot for all architectures. To build
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 created.
 
 Uploading new images to Google Clound Storage requires write permission on the
 `chrome-linux-sysroot` bucket.
 
 ### Rolling the sysroot version used by chromium
 
 Once new images have been uploaded the `install-sysroot.py` script needs to be
 updated to reference the new versions.  This process is manual and involves
 updating the `REVISION` and `SHA1SUM` variables in the script.