coala/docs: Add position number convention

Added a note in Writing_Native_Bears.rst and a reminder
for developers in Writing_Linter_Bears.rst files.

Fixes coala#5297

docs/Developers/Writing_Linter_Bears.rst

@@ -145,6 +145,11 @@ that is printed out.
 For the exact list of named groups ``@linter`` recognizes, see the `API
 documentation <https://api.coala.io/en/latest/>`__.
 
+Pylint uses 0-based column convention and 1-based line convention. 
+We need to map linter's convention to coala's, please refer to 
+`Normalize line or Column convention <https://coala-api.netlify.com/developers/
+writing_linter_bears#normalize-line-or-column-numbers>`__.
+
 Please refer to `Python3 re module <https://docs.python.org/3/library/re.html>`_
 and `Dive into python <http://www.diveintopython3.net/regular-expressions.html>`_
 for information about regular expressions.

docs/Developers/Writing_Native_Bears.rst

@@ -598,4 +598,7 @@ For example, let's make an aspect bear named SpellingCheckBear.
                         aspect=DictionarySpelling('py'),
                     )
 
+.. note::
+    Coala uses 1-based line & column convention, i.e. the first line and first column are 1. However, some linter use 0-based convention. For example ``pylint`` uses 1-based line convention and 0-based column convention. We need to map these conventions, please refer to `Normalize line or Column convention <https://coala-api.netlify.com/developers/writing_linter_bears#normalize-line-or-column-numbers>`__.
+
 .. _main tutorial: https://docs.coala.io/en/latest/Users/Tutorial.html