checkpatch: add checkpatch.sh README and correct some typos

Change-Id: Ib917dae235dc42fa2fa29e40c925f8fd048131df
Signed-off-by: liuhaitao <liuhaitao@xiaomi.com>

tools/README.txt

@@ -26,6 +26,25 @@ Config.mk
   Subsequent logic within the configuration-specific Make.defs file may then
   override these default definitions as necessary.
 
+checkpatch.sh
+-------------
+  checkpatch.sh is a bash script that make use of nxstyle and codespell tools
+  to format patches and files conform to NuttX coding standard. For example,
+  it has been used in NuttX github action PR check build.
+
+  $ tools/checkpatch.sh -h
+  USAGE: ./tools/checkpatch.sh [options] [list|-]
+
+  Options:
+  -h
+  -c spell check with codespell(install with: pip install codespell)
+  -r range check only (coupled with -p or -g)
+  -p <patch list> (default)
+  -g <commit list>
+  -f <file list>
+  -  read standard input mainly used by git pre-commit hook as below:
+     git diff --cached | ./tools/checkpatch.sh -
+
 configure.sh
 configure.bat
 configure.c, cfgparser.c, and cfgparser.h

tools/checkpatch.sh

@@ -27,8 +27,8 @@ usage() {
   echo ""
   echo "Options:"
   echo "-h"
-  echo "-c spell check with codespell(install with: pip install codespell"
-  echo "-r range check only (used with -p and -g)"
+  echo "-c spell check with codespell(install with: pip install codespell)"
+  echo "-r range check only (coupled with -p or -g)"
   echo "-p <patch list> (default)"
   echo "-g <commit list>"
   echo "-f <file list>"