fix: inherit process environment and untrack libc objects

programs/man/spawn.2

@@ -59,6 +59,10 @@
     The argument string is set by the parent when calling spawn().
     If no arguments were provided, the buffer will be empty.
 
+    A spawned child inherits a snapshot of its parent's environment. Libc
+    exposes it through getenv(), setenv(), and environ. posix_spawn() can
+    instead provide an explicit envp for the child.
+
 .SH NOTES
     The _start() entry point receives no argc/argv. Use getargs()
     to retrieve the argument string passed by the parent process.