Add steps to use wasm modules with imported memory and imported table

src/SUMMARY.md

@@ -8,4 +8,5 @@
   - [Installing and running tutorial examples](./chapters/tutorial-install.md)
 - [Additional resources](./chapters/additional.md)
   - [Modifying a project that uses Make to compile to Wasm](./chapters/makefile-wasm.md)
+  - [Using a Wasm module with imported memory and imported tables](./chapters/wasm-exported-sandbox.md)
   - [More tutorials](chapters/appendix.md)

src/chapters/additional.md

@@ -0,0 +1 @@
+# Additional resources

src/chapters/wasm-exported-sandbox.md

@@ -0,0 +1,11 @@
+# Using a Wasm module with imported memory and imported tables
+
+By default, RLBox operates on Wasm modules with an imported memory and imported
+table. This allows RLBox to optimize the memory allocation's alignment for its
+internal operations. However, you can also use modules with exported memory and
+exported tables (albeit with some performance penalty).
+
+To do this, adjust the flags during the compilation of your Wasm module to
+export memory and tables. Specifically, remove the arguments
+`-Wl,--import-memory -Wl,--import-table` if present, and use the arguments
+`-Wl,--export-all -Wl,--export-table`

src/chapters/wasm-sandbox.md

@@ -76,8 +76,12 @@ wasi-clang will link wasi-libc (a custom version of musl) with your library
 instead of the system `libc`. The wasi-libc library and headers live in
 `$WASI_SYSROOT`
 
-Also note worthy are the `$(WASM_CFLAGS)` which are important to ensure that
-our output plays nicely with the rest of the toolchain.
+Also note worthy are the `$(WASM_CFLAGS)` which are important to ensure that our
+output plays nicely with the rest of the toolchain. By default, the flags we use
+forces the Wasm module to use an "imported" memory allocation and "imported"
+indirection function table that is created by RLBox for optimal performance.
+(See [Using a Wasm module with imported memory and imported tables](./wasm-exported-sandbox.md)
+for other options)
 
 <!-- XXX explain flags -->