Add README.md to maelstrom-worker-child.

crates/maelstrom-worker-child/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "maelstrom-worker-child"
-description = "No_std worker code that is run in the child process"
+description = "No_std worker code that is run in the child process."
 documentation.workspace = true
 edition.workspace = true
 homepage.workspace = true

crates/maelstrom-worker-child/README.md

@@ -0,0 +1,11 @@
+# Maelstrom Worker Child
+
+This is a small library that is only intended to be used by the
+[maelstrom-worker](../maelstrom-worker). It is its own library so it can
+be `no_std` and we can ensure that it doesn't take any undesired dependencies.
+
+This library is instended to be used in the child processes after a `clone`
+syscall in potentially-multithreaded processes. The child process in this case
+is very limited in what it can do without potentially blocking. For example,
+even allocations are disallowed. This library just executes a series of
+syscalls, the last of which should be `execve`.