agy: add page (#22314)

Co-authored-by: Lena Pastwa <lena@lnps.me>

pages/common/agy.md

@@ -0,0 +1,28 @@
+# agy
+
+> An agentic development platform by Google.
+> More information: <https://antigravity.google/docs>.
+
+- Open a specific file or directory:
+
+`agy {{path/to/file_or_directory}}`
+
+- Compare two files with each other:
+
+`agy {{[-d|--diff]}} {{path/to/file1}} {{path/to/file2}}`
+
+- Pass in a prompt to run in a chat session in the current working directory:
+
+`agy chat "{{prompt}}"`
+
+- Install or uninstall a specific extension:
+
+`agy --{{install|uninstall}}-extension {{publisher.extension|path/to/extension.vsix}}`
+
+- Add an MCP (Model Context Protocol) server definition to the user profile:
+
+`agy --add-mcp "{{json_string}}"`
+
+- Display help:
+
+`agy {{[-h|--help]}}`