docs/DYNBUF: clarify documentation for Curl_dyn_ptr and Curl_dyn_uptr

Closes #8606

docs/DYNBUF.md

@@ -84,9 +84,9 @@ larger than the buffer length.
 char *Curl_dyn_ptr(const struct dynbuf *s);
 ```
 
-Returns a `char *` to the buffer if it has a length, otherwise a NULL. Since
-the buffer may be reallocated, this pointer should not be trusted or used
-anymore after the next buffer manipulation call.
+Returns a `char *` to the buffer if it has a length, otherwise may return
+NULL. Since the buffer may be reallocated, this pointer should not be trusted
+or used anymore after the next buffer manipulation call.
 
 ## uptr
 
@@ -94,9 +94,9 @@ anymore after the next buffer manipulation call.
 unsigned char *Curl_dyn_uptr(const struct dynbuf *s);
 ```
 
-Returns an `unsigned char *` to the buffer if it has a length, otherwise a
-NULL. Since the buffer may be reallocated, this pointer should not be trusted
-or used anymore after the next buffer manipulation call.
+Returns an `unsigned char *` to the buffer if it has a length, otherwise may
+return NULL. Since the buffer may be reallocated, this pointer should not be
+trusted or used anymore after the next buffer manipulation call.
 
 ## len