typo fix (#2703)

Author: akhmerov

docs/usage/package_server.md

@@ -1,4 +1,4 @@
-# Packagve Server
+# Package Server
 
 Emscripten-forge packages are hosted on  [prefix.dev](https://prefix.dev/channels/emscripten-forge-dev).
 
@@ -11,4 +11,4 @@ Emscripten-forge packages are hosted on  [prefix.dev](https://prefix.dev/channel
         -c https://prefix.dev/channels/emscripten-forge-dev \
         -c conda-forge \
         python numpy
-    ```
+    ```