Set codespell dictionary from environment

This commit reverts the removal of this feature in:
3eaa47e ("Remove codespellfile setting from .checkpatch")

Change-Id: I8184b8cc6cb57e772e576bde439bada69bb1b779
Signed-off-by: Gabor Toth <gabor.toth2@arm.com>
diff --git a/.checkpatch b/.checkpatch
index dd8dad9..4d69058 100644
--- a/.checkpatch
+++ b/.checkpatch
@@ -7,6 +7,8 @@
 
 --showfile
 --codespell
+# Please set CODESPELL_FILE in the environment.
+--codespellfile="$CODESPELL_FILE"
 --ignore SPDX_LICENSE_TAG,PREFER_KERNEL_TYPES,USLEEP_RANGE,GERRIT_CHANGE_ID,FILE_PATH_CHANGES,UNNECESSARY_PARENTHESES,PREFER_DEFINED_ATTRIBUTE_MACRO,BIT_MACRO
 --no-tree
 --terse
diff --git a/docs/project/quality-assurance/verification-methodology.rst b/docs/project/quality-assurance/verification-methodology.rst
index f68401d..ce421e8 100644
--- a/docs/project/quality-assurance/verification-methodology.rst
+++ b/docs/project/quality-assurance/verification-methodology.rst
@@ -19,7 +19,8 @@
   - spelling mistakes
   - git commit message formatting
 
-Please find the configuration of this tool in the :download:`TS repository.<../../../.checkpatch>`
+Please find the configuration of this tool in the :download:`TS repository.<../../../.checkpatch>` but do not forget
+to set ``CODESPELL_FILE`` variable in the environment to the local copy of the `codespell dictionary v2.3.0`_.
 
 Cppcheck tool
 '''''''''''''
@@ -65,6 +66,7 @@
 
 .. _`Checkpatch`: https://docs.kernel.org/dev-tools/checkpatch.html
 .. _`CppCheck`: https://cppcheck.sourceforge.io/
+.. _`codespell dictionary v2.3.0`: https://raw.githubusercontent.com/codespell-project/codespell/v2.3.0/codespell_lib/data/dictionary.txt
 
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