Fix a typo (#3043)

* Fix a typo

* Fix a typo

* Fix abroken link

docs/source/extending/keymaps.rst

@@ -7,7 +7,7 @@ Customize keymaps
     which is not guaranteed to be kept in future versions of the notebook,
     and can be removed or changed without warnings.
 
-The notebook shortcuts that are defined by jupyter both in edit mode an command
+The notebook shortcuts that are defined by jupyter both in edit mode and command
 mode are configurable in the frontend configuration file
 ``~/.jupyter/nbconfig/notebook.json``. The modification of Keyboard shortcut
 suffer of several limitations, mainly that your Browser and OS might prevent

notebook/serverextensions.py

@@ -283,8 +283,8 @@ class ServerExtensionApp(BaseExtensionApp):
     examples = _examples
 
     subcommands = dict(
-        enable=(EnableServerExtensionApp, "Enable an server extension"),
-        disable=(DisableServerExtensionApp, "Disable an server extension"),
+        enable=(EnableServerExtensionApp, "Enable a server extension"),
+        disable=(DisableServerExtensionApp, "Disable a server extension"),
         list=(ListServerExtensionsApp, "List server extensions")
     )
 

notebook/static/tree/js/main.js

@@ -196,7 +196,7 @@ require([
         e.preventDefault();
 
         // Set the hash without causing the page to jump.
-        // http://stackoverflow.com/a/14690177/2824256
+        // https://stackoverflow.com/a/14690177/2824256
         var hash = $(this).attr("href");
         if(window.history.pushState) {
             window.history.pushState(null, null, hash);