Minor documentation fixes

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

scripts/mbedtls_dev/c_build_helper.py

diff --git a/scripts/mbedtls_dev/c_build_helper.py b/scripts/mbedtls_dev/c_build_helper.py
index 6807602..5c587a1 100644
--- a/scripts/mbedtls_dev/c_build_helper.py
+++ b/scripts/mbedtls_dev/c_build_helper.py
@@ -103,7 +103,7 @@
     * ``header``: extra code to insert before any function in the generated
       C file.
     * ``expressions``: a list of C language expressions that have the type
-      ``type``.
+      ``cast_to``.
     * ``include_path``: a list of directories containing header files.
     * ``keep_c``: if true, keep the temporary C file (presumably for debugging
       purposes).

tests/scripts/check-python-files.sh

diff --git a/tests/scripts/check-python-files.sh b/tests/scripts/check-python-files.sh
index 03a1472..11e351b 100755
--- a/tests/scripts/check-python-files.sh
+++ b/tests/scripts/check-python-files.sh
@@ -29,7 +29,8 @@
 fi
 
 can_pylint () {
-    # Pylint 1.5.2 from Ubuntu 16.04 is too old.
+    # Pylint 1.5.2 from Ubuntu 16.04 is too old:
+    #     E: 34, 0: Unable to import 'mbedtls_dev' (import-error)
     # Pylint 1.8.3 from Ubuntu 18.04 passed on the first commit containing this line.
     $PYTHON -m pylint 2>/dev/null --version | awk '
         BEGIN {status = 1}
@@ -45,7 +46,7 @@
 can_mypy () {
     # Just check that mypy is present and looks sane. I don't know what
     # minimum version is required. The check is not just "type mypy"
-    # becaues that passes if a mypy exists but is not installed for the current
+    # because that passes if a mypy exists but is not installed for the current
     # python version.
     mypy --version 2>/dev/null >/dev/null
 }

tests/scripts/test_psa_constant_names.py

diff --git a/tests/scripts/test_psa_constant_names.py b/tests/scripts/test_psa_constant_names.py
index 694e2a9..5de59c2 100755
--- a/tests/scripts/test_psa_constant_names.py
+++ b/tests/scripts/test_psa_constant_names.py
@@ -306,7 +306,7 @@
     return inputs
 
 def run_c(type_word, expressions, include_path=None, keep_c=False):
-    """Generate and run a program to print out numerical values for expressions."""
+    """Generate and run a program to print out numerical values of C expressions."""
     if type_word == 'status':
         cast_to = 'long'
         printf_format = '%ld'