dev/test/ref-manual: Fix typos

Fix some typos.
s/necesary/necessary/
s/overriden/overridden/

(From yocto-docs rev: f4ce6ae80b1d96f9b8bead013642aeda0c776182)

Signed-off-by: Naoki Hayama <naoki.hayama@lineo.co.jp>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/dev-manual/dev-manual-common-tasks.rst

@@ -9477,7 +9477,7 @@ been parsed. The variables include those from the configuration as well:
 
 In the output of ``bitbake -e``, each variable is preceded by a
 description of how the variable got its value, including temporary
-values that were later overriden. This description also includes
+values that were later overridden. This description also includes
 variable flags (varflags) set on the variable. The output can be very
 helpful during debugging.
 

documentation/ref-manual/ref-variables.rst

@@ -4660,7 +4660,7 @@ system and gives an overview of their function and contents.
          MACHINEOVERRIDES =. "qemuall:"
 
       This
-      override allows variables to be overriden for all machines emulated
+      override allows variables to be overridden for all machines emulated
       in QEMU, like in the following example from the ``connman-conf``
       recipe:
       ::

documentation/test-manual/test-manual-understand-autobuilder.rst

@@ -164,7 +164,7 @@ Cloning repositories from scratch each time they are required was slow
 on the Autobuilder. We therefore have a stash of commonly used
 repositories pre-cloned on the Workers. Data is fetched from these
 during clones first, then "topped up" with later revisions from any
-upstream when necesary. The cache is maintained by the Autobuilder
+upstream when necessary. The cache is maintained by the Autobuilder
 Worker Janitor. See :ref:`test-manual/test-manual-understand-autobuilder:Autobuilder Worker Janitor`.
 
 .. _test-autobuilder-worker-janitor: