Document SIZE_MAX requirement in README.md
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/README.md b/README.md
index 7b45a1f..f4bf4e1 100644
--- a/README.md
+++ b/README.md
@@ -264,6 +264,7 @@
- `int` and `size_t` must be at least 32 bits wide.
- The types `uint8_t`, `uint16_t`, `uint32_t` and their signed equivalents must be available.
- Mixed-endian platforms are not supported.
+- SIZE_MAX must be at least as big as INT_MAX and UINT_MAX.
PSA cryptography API
--------------------