new Copilot page

content/en/usage/copilot.md

@@ -0,0 +1,50 @@
+---
+title: Copilot
+weight: 20
+---
+
+Lem supports Copilot completions.
+
+While editing a source file, Lem shows completions in an
+overlay. Below it suggests a function body for factorial, and we see
+Lem's function signature default help.
+
+<a href="/copilot.png"> <img class="" src="/copilot.png" alt="Lem suggests GitHub Copilot completions in an overlay." style="max-width: 60%"> </a>
+
+You might need to install the Copilot dependencies (see below).
+
+## Login
+
+To login, use `M-x copilot-login`.
+
+After logging in, open a source file and edit it. The completion will be performed.
+
+## Browsing and accepting changes
+
+Use `Tab` to accept a suggestion (`copilot-accept-suggestion`)
+
+See the next suggestion with `M-n` (`copilot-next-suggestion`),
+
+see the previous one with `M-p`.
+
+
+## Other commands
+
+`M-x copilot-install-server`: install the required npm `copilot-node-server` dependency.
+
+`M-x copilot-restart`: restart the Copilot process.
+
+
+## Configuration
+
+Lem's Copilot mode uses the `*copilot-completion-keymap*` keymap to
+define keys, inside the Lisp package `lem-copilot`.
+
+You can change `copilot-suggestion-attribute` that defaults to "dark gray":
+
+```lisp
+(define-attribute copilot-suggestion-attribute
+  (t :foreground "dark gray"))
+```
+
+You can find logs in the `copilot/` directory of your `(lem-home)`.