fix(docs-infra): add shell to the list of code-example languages re…

…cognized as cli commands (#45551) (#45563)

Previously, only `language="sh"` and `language="bash"` would be
recognized (and formatted) as cli commands in `<code-example>`.

This commit adds `shell` to the list of languages recognized as cli
commands.

(NOTE: This will fix the [CI failures][1] in #45325.)

[1]: https://circleci.com/gh/angular/angular/1145559

PR Close #45551

PR Close #45563

aio/src/styles/2-modules/code/_code-theme.scss

@@ -13,6 +13,7 @@
     }
 
     // TERMINAL / SHELL TEXT STYLES
+    &[language="shell"],
     &[language="sh"],
     &[language="bash"] {
       background-color: constants.$darkgray;
@@ -201,6 +202,7 @@
   /* SHELL / TERMINAL CODE BLOCKS */
 
   code-example {
+    &[language="shell"],
     &[language="sh"],
     &[language="bash"] {
       .pnk,

aio/src/styles/_print.scss

@@ -105,7 +105,9 @@
   }
 
   code-example {
-    &[language=sh], &[language=bash] {
+    &[language=shell],
+    &[language=sh],
+    &[language=bash] {
       background: none;
 
       .pnk,