Fix a/an typos in doxygen and other comments
Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/include/mbedtls/asn1write.h b/include/mbedtls/asn1write.h
index d60ca0d..5554720 100644
--- a/include/mbedtls/asn1write.h
+++ b/include/mbedtls/asn1write.h
@@ -86,7 +86,7 @@
#if defined(MBEDTLS_BIGNUM_C)
/**
- * \brief Write a arbitrary-precision number (#MBEDTLS_ASN1_INTEGER)
+ * \brief Write an arbitrary-precision number (#MBEDTLS_ASN1_INTEGER)
* in ASN.1 format.
*
* \note This function works backwards in data buffer.