Add cargo jinstall-lsp as a shorthand to include jemalloc support

.cargo/config

@@ -5,6 +5,8 @@ gen-syntax   = "run --package tools --bin tools -- gen-syntax"
 gen-tests    = "run --package tools --bin tools -- gen-tests"
 # Installs ra_lsp_server
 install-lsp = "install --path crates/ra_lsp_server --force"
+# Installs ra_lsp_server with the jemalloc feature
+jinstall-lsp = "install --path crates/ra_lsp_server --force --features jemalloc"
 # Installs the visual studio code extension
 install-code = "run --package tools --bin tools -- install-code"
 # Formats the full repository or installs the git hook to do it automatically.

ARCHITECTURE.md

@@ -178,7 +178,7 @@ VS Code plugin
 
 To try out VS Code extensions, run `cargo install-code`.  This installs both the
 `ra_lsp_server` binary and the VS Code extension. To install only the binary, use
-`cargo install --path crates/ra_lsp_server --force`
+`cargo install-lsp` (shorthand for `cargo install --path crates/ra_lsp_server --force`)
 
 To see logs from the language server, set `RUST_LOG=info` env variable. To see
 all communication between the server and the client, use
@@ -186,12 +186,12 @@ all communication between the server and the client, use
 
 There's `rust-analyzer: status` command which prints common high-level debug
 info. In particular, it prints info about memory usage of various data
-structures, and, if compiled with jemalloc support (`cargo install --features
-jemalloc`), the summary statistic about the heap.
+structures, and, if compiled with jemalloc support (`cargo jinstall-lsp` or 
+`cargo install --path crates/ra_lsp_server --force --features jemalloc`), includes
+ statistic about the heap.
 
 To run tests, just `cargo test`.
 
 To work on the VS Code extension, launch code inside `editors/code` and use `F5` to
 launch/debug. To automatically apply formatter and linter suggestions, use `npm
 run fix`.
-