Added linter installing methods

doc/ale-cloudformation.txt

@@ -7,23 +7,40 @@ cfn-python-lint                             *ale-cloudformation-cfn-python-lint*
 
 cfn-python-lint is a linter for AWS CloudFormation template file.
 
-https://github.com/awslabs/cfn-python-lint
-===============================================================================
-Getting it to work:                            *ale-cloudformation-activate*
+Website: https://github.com/awslabs/cfn-python-lint
 
-To get cloudformation linter to work on only CloudFormation files put 
+Installation
+-------------------------------------------------------------------------------
+
+
+Install cfn-python-lint using either pip or brew: >
+
+`pip install cfn-lint`. If pip is not available, run
+`python setup.py clean --all` then `python setup.py install`.
+
+ Homebrew (macOS):
+
+`brew install cfn-lint`
+
+<
+Configuration
+-------------------------------------------------------------------------------
+
+To get cloudformation linter to work on only CloudFormation files  we must set
+the buffer |filetype| to yaml.cloudformation.
+This causes ALE to lint the file with linters configured for cloudformation and
+yaml files.
+
+Just put:
+
+>
 
  au BufRead,BufNewFile *.template.yaml set filetype=yaml.cloudformation
 
+<
+
 on `ftdetect/cloudformation.vim`
 
-and 
-
-let b:ale_linter_aliases = {'cloudformation': ['cloudformation', 'yaml']}
-
-on `after/ftplugin/yaml.vim`
-
-This will get both cloudformation and yaml linters on work on any file with `template.yaml` ext.
+This will get both cloudformation and yaml linters to work on any file with `.template.yaml` ext.
 ===============================================================================
   vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:
-