Docs: Improve the documentation for kittens

Add more text roles and links.
Add an example that broadcasts only to other windows in the current tab.
Initial capitalization of the key names in the kbd text role.
Add Python type hints for custom kittens.
Note about hyperlink support for ls on macOS.
Add description text for show_key.

docs/kittens/diff.rst

@@ -12,8 +12,8 @@ Major Features
 
     * Displays diffs side-by-side in the kitty terminal
 
-    * Does syntax highlighting of the displayed diffs, asynchronously, for maximum
-      speed
+    * Does syntax highlighting of the displayed diffs, asynchronously, for
+      maximum speed
 
     * Displays images as well as text diffs, even over SSH
 
@@ -31,11 +31,11 @@ Major Features
 Installation
 ---------------
 
-Simply :ref:`install kitty <quickstart>`.  You also need
-to have either the `git <https://git-scm.com/>`_ program or the ``diff`` program
-installed. Additionally, for syntax highlighting to work,
-`pygments <https://pygments.org/>`_ must be installed (note that pygments is
-included in the official kitty binary builds).
+Simply :ref:`install kitty <quickstart>`.  You also need to have either the `git
+<https://git-scm.com/>`__ program or the :program:`diff` program installed.
+Additionally, for syntax highlighting to work, `pygments
+<https://pygments.org/>`__ must be installed (note that pygments is included in
+the official kitty binary builds).
 
 
 Usage
@@ -45,9 +45,10 @@ In the kitty terminal, run::
 
     kitty +kitten diff file1 file2
 
-to see the diff between file1 and file2.
+to see the diff between :file:`file1` and :file:`file2`.
 
-Create an alias in your shell's startup file to shorten the command, for example:
+Create an alias in your shell's startup file to shorten the command, for
+example:
 
 .. code-block:: sh
 
@@ -67,20 +68,20 @@ Keyboard controls
 =========================   ===========================
 Action                      Shortcut
 =========================   ===========================
-Quit                        :kbd:`q`, :kbd:`ctrl+c`, :kbd:`Esc`
-Scroll line up              :kbd:`k`, :kbd:`Up`
-Scroll line down            :kbd:`j`, :kbd:`Down`
+Quit                        :kbd:`Q`, :kbd:`Ctrl+C`, :kbd:`Esc`
+Scroll line up              :kbd:`K`, :kbd:`Up`
+Scroll line down            :kbd:`J`, :kbd:`Down`
 Scroll page up              :kbd:`PgUp`
 Scroll page down            :kbd:`PgDn`
 Scroll to top               :kbd:`Home`
 Scroll to bottom            :kbd:`End`
 Scroll to next page         :kbd:`Space`, :kbd:`PgDn`
 Scroll to previous page     :kbd:`PgUp`
-Scroll to next change       :kbd:`n`
-Scroll to previous change   :kbd:`p`
+Scroll to next change       :kbd:`N`
+Scroll to previous change   :kbd:`P`
 Increase lines of context   :kbd:`+`
 Decrease lines of context   :kbd:`-`
-All lines of context        :kbd:`a`
+All lines of context        :kbd:`A`
 Restore default context     :kbd:`=`
 Search forwards             :kbd:`/`
 Search backwards            :kbd:`?`
@@ -93,7 +94,7 @@ Scroll to previous match    :kbd:`<`, :kbd:`,`
 Integrating with git
 -----------------------
 
-Add the following to `~/.gitconfig`:
+Add the following to :file:`~/.gitconfig`:
 
 .. code-block:: ini
 
@@ -119,24 +120,23 @@ Why does this work only in kitty?
 ----------------------------------------
 
 The diff kitten makes use of various features that are :doc:`kitty only
-</protocol-extensions>`,  such as the :doc:`kitty graphics protocol
+</protocol-extensions>`, such as the :doc:`kitty graphics protocol
 </graphics-protocol>`, the :doc:`extended keyboard protocol
-</keyboard-protocol>`, etc. It also leverages terminal program
-infrastructure I created for all of kitty's other kittens to reduce the amount
-of code needed (the entire implementation is under 2000 lines of code).
+</keyboard-protocol>`, etc. It also leverages terminal program infrastructure
+I created for all of kitty's other kittens to reduce the amount of code needed
+(the entire implementation is under 2000 lines of code).
 
 And fundamentally, it's kitty only because I wrote it for myself, and I am
 highly unlikely to use any other terminals :)
 
 
-
 Configuration
 ------------------------
 
 You can configure the colors used, keyboard shortcuts, the diff implementation,
-the default lines of context, etc.  by creating a :file:`diff.conf` file in
-your :ref:`kitty config folder <confloc>`. See below for the supported
-configuration directives.
+the default lines of context, etc. by creating a :file:`diff.conf` file in your
+:ref:`kitty config folder <confloc>`. See below for the supported configuration
+directives.
 
 
 .. include:: /generated/conf-kitten-diff.rst
@@ -145,7 +145,6 @@ configuration directives.
 .. include:: /generated/cli-kitten-diff.rst
 
 
-
 Sample diff.conf
 -----------------