Clarify limits of dependencies table support

Author: awvwgk

manifest-reference.md

@@ -226,6 +226,8 @@ The source file containing the program body can be specified in the *main* entry
 Executables can have their own dependencies.
 See [specifying dependencies](#specifying-dependencies) for more details.
 
+> Dependencies supported in Bootstrap fpm only
+
 *Example:*
 
 ```toml
@@ -263,6 +265,8 @@ The source file containing the program body can be specified in the *main* entry
 Tests can have their own dependencies.
 See [specifying dependencies](#specifying-dependencies) for more details.
 
+> Dependencies supported in Bootstrap fpm only
+
 *Example:*
 
 ```toml