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

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

docs/source/tutorial/tutorial01.rst

@@ -138,22 +138,22 @@ Let's Backup that Database!
 **Senior**
 
   Not at all.  The creators of *Kapow!* have thought of everything.  You can put
-  all your route definitions in a special script file and pass it to the server
-  on startup.  They call those files :file:`pow` files and they have
-  :file:`.pow` extension.
+  all your route definitions on init programs, which can be shell scripts, and
+  pass them to the server on startup.
 
   It should look something like:
 
   .. code-block:: console
 
-     $ cat backup.pow
+     $ cat backup-route
+     #!/usr/bin/env sh
      kapow route add -X PUT /db/backup -e ./backup_db.sh
 
   And then you can start *Kapow!* with it:
 
   .. code-block:: console
 
-     $ kapow server backup.pow
+     $ kapow server backup-route
 
 **Junior**
 
@@ -161,10 +161,10 @@ Let's Backup that Database!
 
   .. code-block:: console
 
-     $ kapow server backup.pow
-     2019/11/26 11:40:01 Running powfile: "backup.pow"
+     $ kapow server backup-route
+     2019/11/26 11:40:01 Running init program: "backup-route"
      {"id":"19bb4ac7-1039-11ea-aa00-106530610c4d","method":"PUT","url_pattern":"/db/backup","entrypoint":"./backup_db.sh","command":"","index":0}
-     2019/11/26 11:40:01 Done running powfile: "backup.pow"
+     2019/11/26 11:40:01 Done running init program: "backup-route"
 
   I understand that this is proof that we have the endpoint available.
 

docs/source/tutorial/tutorial02.rst

@@ -37,10 +37,11 @@ What have we done?
 
 **Junior**
 
-  Let me try add this to our :file:`pow` file:
+  Let me try add this to our init program:
 
   .. code-block:: console
 
+     #!/usr/bin/env sh
      kapow route add /db/backup_logs -c 'cat /tmp/backup_db.log | kapow set /response/body'
 
 **Senior**

docs/source/tutorial/tutorial06.rst

@@ -44,7 +44,9 @@ Securing the server
 
   .. code-block:: console
 
-     $ kapow server --keyfile /etc/kapow/tls/keyfile --certfile /etc/kapow/tls/certfile /etc/kapow/awesome.pow
+     $ kapow server --keyfile /etc/kapow/tls/keyfile    \
+                    --certfile /etc/kapow/tls/certfile  \
+                    /etc/kapow/awesome-route
 
   It's easy, please copy the private key file and certificate chain to `/etc/kapow/tls` and we can restart.
 
@@ -70,7 +72,11 @@ Securing the server
 
   .. code-block:: console
 
-     $ kapow server --keyfile /etc/kapow/tls/keyfile --certfile /etc/kapow/tls/certfile --clientauth=true --clientcafile /etc/kapow/tls/clientCAfile /etc/kapow/awesome.pow
+     $ kapow server --keyfile /etc/kapow/tls/keyfile            \
+                    --certfile /etc/kapow/tls/certfile          \
+                    --clientauth true                           \
+                    --clientcafile /etc/kapow/tls/clientCAfile  \
+                    /etc/kapow/awesome-route
 
   Done!