docs: clarify SSR/WASM binary size comments

docs/book/src/appendix_binary_size.md

@@ -37,11 +37,18 @@ To do this, create a file in your project at `.cargo/config.toml`
 
 ```toml
 [unstable]
-[target.'cfg(target_arch = "wasm32")']
 build-std = ["std", "panic_abort", "core", "alloc"]
 build-std-features = ["panic_immediate_abort"]
 ```
 
+Note that if you're using this with SSR too, the same Cargo profile will be applied. You'll need to explicitly specify your target:
+```toml
+[build]
+target = "x86_64-unknown-linux-gnu" # or whatever
+```
+
+And you'll need to add `panic = "abort"` to `[profile.release]` in `Cargo.toml`. Note that this applies the same `build-std` and panic settings to your server binary, which may not be desirable. Some further exploration is probably needed here.
+
 5. One of the sources of binary size in WASM binaries can be `serde` serialization/deserialization code. Leptos uses `serde` by default to serialize and deserialize resources created with `create_resource`. You might try experimenting with the `miniserde` and `serde-lite` features, which allow you to use those crates for serialization and deserialization instead; each only implements a subset of `serde`’s functionality, but typically optimizes for size over speed.
 
 ## Things to Avoid