Use correct syntax markup for shell

Approved by:	carlavilla

documentation/content/en/articles/nanobsd/_index.adoc

@@ -61,7 +61,7 @@ The configuration file partition persists under the [.filename]#/cfg# directory.
 [example]
 ====
 
-[source,bash]
+[source,shell]
 ....
 # vi /etc/resolv.conf
 [...]
@@ -85,7 +85,7 @@ A NanoBSD image is built using a simple [.filename]#nanobsd.sh# shell script, wh
 
 The necessary commands to build a NanoBSD image are:
 
-[source,bash]
+[source,shell]
 ....
 # cd /usr/src/tools/tools/nanobsd <.>
 # sh nanobsd.sh <.>
@@ -155,7 +155,7 @@ This is probably the most important and most interesting feature of NanoBSD. Thi
 
 Invocation of the following command will force the [.filename]#nanobsd.sh# to read its configuration from [.filename]#myconf.nano# located in the current directory:
 
-[source,bash]
+[source,shell]
 ....
 # sh nanobsd.sh -c myconf.nano
 ....
@@ -350,7 +350,7 @@ According to which services are available on host serving new NanoBSD image and
 
 If the transfer speed is in first place, use this example:
 
-[source,bash]
+[source,shell]
 ....
 # ftp myhost
 get _.disk.image "| sh updatep1"
@@ -360,7 +360,7 @@ get _.disk.image "| sh updatep1"
 
 If a secure transfer is preferred, consider using this example:
 
-[source,bash]
+[source,shell]
 ....
 # ssh myhost cat _.disk.image.gz | zcat | sh updatep1
 ....
@@ -373,7 +373,7 @@ Try this example if the remote host is not running neither man:ftpd[8] or man:ss
 ====
 . At first, open a TCP listener on host serving the image and make it send the image to client:
 +
-[source,bash]
+[source,shell]
 ....
 myhost# nc -l 2222 < _.disk.image
 ....
@@ -384,7 +384,7 @@ Make sure that the used port is not blocked to receive incoming connections from
 ======
 . Connect to the host serving new image and execute [.filename]#updatep1# script:
 +
-[source,bash]
+[source,shell]
 ....
 # nc myhost 2222 | sh updatep1
 ....