Redesign yamllint config for Travis CI config

Signed-off-by: 林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

Author: brlin-tw

.yamllint

@@ -1,48 +1,135 @@
-# Configuration File for yamllint(1)
+%YAML 1.2
 ---
+# Configuration File of yamllint for Travis CI configurations and similarly relaxed YAML documents
+# https://github.com/Lin-Buo-Ren/Configuration-Templates-for-Travis-CI
+#
+# This file is in YAML Ain’t Markup Language (YAML™)
+# http://yaml.org/
+#
+# This file is based on the `default` pre-defined configuration from yamllint with documentation copied from its documentation
+# https://yamllint.readthedocs.io/en/stable/configuration.html#default-configuration
+#
+# This file is based on The Unofficial yamllint Configuration Templates
+# https://github.com/Lin-Buo-Ren/yamllint-configuration-templates
 rules:
+  # Use this rule to control the number of spaces inside braces (`{` and `}`).
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.braces
   braces:
     min-spaces-inside: 0
     max-spaces-inside: 0
     min-spaces-inside-empty: -1
     max-spaces-inside-empty: -1
+
+  # Use this rule to control the number of spaces inside brackets (`[` and `]`).
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.brackets
   brackets:
     min-spaces-inside: 0
     max-spaces-inside: 0
     min-spaces-inside-empty: -1
     max-spaces-inside-empty: -1
+
+  # Use this rule to control the number of spaces before and after colons (`:`).
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.colons
   colons:
     max-spaces-before: 0
     max-spaces-after: 1
+
+  # Use this rule to control the number of spaces before and after commas (`,`).
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.commas
   commas:
     max-spaces-before: 0
     min-spaces-after: 1
     max-spaces-after: 1
+
+  # Use this rule to control the position and formatting of comments.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.comments
   comments:
     level: warning
+    # PATCH: Comments without separate space are disabled content
     require-starting-space: false
+    # PATCH: We're good with 1
     min-spaces-from-content: 1
+
+  # Use this rule to force comments to be indented like content.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.comments_indentation
+  # PATCH: False positives, disabled
   comments-indentation: disable
+    #level: warning
+
+  # Use this rule to require or forbid the use of document end marker (`...`).
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.document_end
   document-end: disable
-  document-start: disable
+
+  # Use this rule to require or forbid the use of document start marker (`---`).
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.document_start
+  document-start:
+    # PATCH: Travis CI doesn't allow documents with document start markers
+    # https://github.com/travis-ci/travis-ci/issues/9600
+    level: error
+    present: false
+
+  # Use this rule to set a maximal number of allowed consecutive blank lines.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.empty_lines
   empty-lines:
     max: 2
     max-start: 0
     max-end: 0
+
+  # Use this rule to prevent nodes with empty content, that implicitly result in null values.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.empty_values
+  empty-values:
+    forbid-in-block-mappings: false
+    forbid-in-flow-mappings: false
+
+  # Use this rule to control the number of spaces after hyphens (`-`).
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.hyphens
   hyphens:
     max-spaces-after: 1
+
+  # Use this rule to control the indentation.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.indentation
   indentation:
     spaces: consistent
     indent-sequences: consistent
     check-multi-line-strings: false
+
+  # Use this rule to prevent multiple entries with the same key in mappings.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.key_duplicates
   key-duplicates: enable
+
+  # Use this rule to enforce alphabetical ordering of keys in mappings. The sorting order uses the Unicode code point number. As a result, the ordering is case-sensitive and not accent-friendly (see examples below).
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.key_ordering
+  key-ordering: disable
+
+  # Use this rule to set a limit to lines length.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.line_length
   line-length:
-    max: 9999
+    # PATCHED: Modern text editors handle long lines nicely
+    max: 99999
     allow-non-breakable-words: true
     allow-non-breakable-inline-mappings: false
+
+  # Use this rule to require a new line character (`\n`) at the end of files.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.new_line_at_end_of_file
   new-line-at-end-of-file: enable
+
+  # Use this rule to force the type of new line characters.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.new_lines
   new-lines:
     type: unix
+
+  # Use this rule to prevent values with octal numbers. In YAML, numbers that start with `0` are interpreted as octal, but this is not always wanted. For instance `010` is the city code of Beijing, and should not be converted to `8`.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.octal_values
+  octal-values:
+    forbid-implicit-octal: false
+    forbid-explicit-octal: false
+
+  # Use this rule to forbid trailing spaces at the end of lines.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.trailing_spaces
   trailing-spaces: enable
+
+  # Use this rule to forbid non-explictly typed truthy values other than `true` and `false`, for example `YES`, `False` and `off`.
+  # https://yamllint.readthedocs.io/en/stable/rules.html#module-yamllint.rules.truthy
   truthy:
-    level: warning
+    level: warning
+...