doc: drop mentions to .pow files ($deity REST their soul)

Co-authored-by: Roberto Abdelkader Martínez Pérez <robertomartinezp@gmail.com>

docs/source/examples/working_with_init_programs.rst

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+Working with Init Scripts
+=========================
+
+Starting *Kapow!* using an init script
+--------------------------------------
+
+An init program, which can be just a shell script, allows you to make calls to
+the ``kapow route`` command.
+
+.. code-block:: console
+   :linenos:
+
+   $ kapow server example-init-program
+
+With the :file:`example-init-program`:
+
+.. code-block:: console
+   :linenos:
+
+   $ cat example-init-program
+   #!/usr/bin/env sh
+   #
+   # This is a simple example of an init program
+   #
+   echo '[*] Starting my init program'
+
+   # We add 2 Kapow! routes
+   kapow route add /my/route -c 'echo hello world | kapow set /response/body'
+   kapow route add -X POST /echo -c 'kapow get /request/body | kapow set /response/body'
+
+.. note::
+
+   *Kapow!* can be fully configured using just init scripts
+
+
+Writing Multiline Routes
+------------------------
+
+If you need to write more complex actions, you can leverage multiline routes:
+
+.. code-block:: console
+   :linenos:
+
+   $ cat multiline-route
+   #!/usr/bin/env sh
+   kapow route add /log_and_stuff - <<-'EOF'
+   	echo this is a quite long sentence and other stuff | tee log.txt | kapow set /response/body
+   	cat log.txt | kapow set /response/body
+   EOF
+
+.. warning::
+
+    Be aware of the **"-"** at the end of the ``kapow route add`` command.
+    It tells ``kapow route add`` to read commands from `stdin`.
+
+.. warning::
+
+    If you want to learn more about multiline usage, see: `Here Doc
+    <https://en.wikipedia.org/wiki/Here_document>`_
+
+
+Keeping Things Tidy
+-------------------
+
+Sometimes things grow, and keeping things tidy is the only way to mantain the
+whole thing.
+
+You can distribute your endpoints in several init programs.  And you can keep
+the whole thing documented in one html file, served with *Kapow!*.
+
+.. code-block:: console
+    :linenos:
+
+    $ cat index-route
+    #!/usr/bin/env sh
+    kapow route add / - <<-'EOF'
+    	cat howto.html | kapow set /response/body
+    EOF
+
+    source ./info_stuff
+    source ./other_endpoints
+
+You can import other shell script libraries with `source`.
+
+
+Debugging Init Programs/Scripts
+-------------------------------
+
+Since *Kapow!* redirects the standard output and the standard error of the init
+program given on server startup to its own, you can leverage ``set -x`` to see
+the commands that are being executed, and use that for debugging.
+
+To support debugging user request executions, the server subcommand has a
+``--debug`` option flag that prompts *Kapow!* to redirect both the script's
+standard output and standard error to *Kapow!*'s standard output, so you can
+leverage ``set -x`` the same way as with init programs.
+
+
+.. code-block:: console
+
+    $ cat withdebug-route
+    #!/usr/bin/env sh
+    kapow route add / - <<-'EOF'
+        set -x
+        echo "This will be seen in the log"
+    	echo "Hi HTTP" | kapow set /response/body
+    EOF
+
+    $ kapow server --debug withdebug-route