chore: improve developer experience (#35)

* chore: ignore files

* doc: how to set AX_CONFIG_PATH

Author: AsakuraMizu

.gitignore

@@ -9,4 +9,5 @@ apps/*/build/
 **/target/
 **/Cargo.lock
 !/vendor/**/Cargo.lock
-/.axconfig.*
+/.axconfig.*
+*.img

README.md

@@ -141,6 +141,17 @@ make ARCH=x86_64 LOG=info AX_TESTCASE=nimbos run
 
 Note: Arguments like `NET`, `BLK`, and `GRAPHIC` enable devices in QEMU, which take effect only at runtime, not at build time. More features can be found in the [Cargo.toml of arceos](https://github.com/oscomp/arceos/blob/main/ulib/axstd/Cargo.toml).
 
+#### Development with Visual Studio Code
+
+Since ArceOS relies on special build scripts and some environment variables, this usually causes `rust-analyzer` to prompt some annoying errors. You may want to put the following configuration into `.vscode/settings.json` (ie workspace settings):
+```json
+{
+  "rust-analyzer.cargo.extraEnv": {
+    "AX_CONFIG_PATH": "${workspaceFolder}/.axconfig.toml"
+  }
+}
+```
+
 ## Test for oscomp testcases
 
 We can run [testcases of the OS competition](https://github.com/oscomp/testsuits-for-oskernel/tree/pre-2025) with StarryOS. Guidence can be found in [Starry-Tutorial](https://azure-stars.github.io/Starry-Tutorial-Book/ch03-02.html). 

apps/oscomp/.gitignore

@@ -0,0 +1,2 @@
+testcase_list
+*.out