Add htmlbeautifier support (#4751)

doc/ale-eruby.txt

@@ -7,6 +7,7 @@ There are four linters for `eruby` files:
 - `erblint`
 - `erubis`
 - `erubi`
+- `htmlbeautifier`
 - `ruumba`
 
 `erb` is in the Ruby standard library and is mostly universal. `erubis` is the
@@ -47,6 +48,18 @@ g:ale_eruby_erblint_options                        *g:ale_ruby_erblint_options*
   This variable can be change to modify flags given to erblint.
 
 
+===============================================================================
+htmlbeautifier                                       *ale-eruby-htmlbeautifier*
+
+g:ale_eruby_htmlbeautifier_executable   *g:ale_eruby_htmlbeautifier_executable*
+                                        *b:ale_eruby_htmlbeautifier_executable*
+  Type: |String|
+  Default: `'htmlbeautifier'`
+
+  Override the invoked htmlbeautifier binary. This is useful for running
+  htmlbeautifier from binstubs or a bundle.
+
+
 ===============================================================================
 ruumba                                                       *ale-eruby-ruumba*
 

doc/ale-supported-languages-and-tools.txt

@@ -182,6 +182,7 @@ Notes:
   * `erblint`
   * `erubi`
   * `erubis`
+  * `htmlbeautifier`
   * `ruumba`
 * Erlang
   * `SyntaxErl`

doc/ale.txt

@@ -3020,6 +3020,7 @@ documented in additional help files.
   eruby...................................|ale-eruby-options|
     erb-formatter.........................|ale-eruby-erbformatter|
     erblint...............................|ale-eruby-erblint|
+    htmlbeautifier........................|ale-eruby-htmlbeautifier|
     ruumba................................|ale-eruby-ruumba|
   fish....................................|ale-fish-options|
     fish_indent...........................|ale-fish-fish_indent|