Add an .editorconfig file to repository

This commit tries to use an editorconfig file to ensure the same
settings across editors while contributing to the vim repository.

The rules are based of the guidelines defined in
`runtime/doc/develop.txt`.

Signed-off-by: Luca Saccarola <github.e41mv@aleeas.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: saccarosium

.editorconfig

@@ -0,0 +1,21 @@
+# https://spec.editorconfig.org/#supported-pairs
+root = true
+
+[*]
+indent_style = tab
+tab_width = 8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.{c,h,proto}]
+indent_size = 4
+
+[*.{md,yml,sh,bat}]
+# This will become the default after we migrate the codebase
+indent_style = space
+indent_size = 2
+
+[*.md]
+# Markdown uses trailing whitespaces to do an hard line break
+# https://spec.commonmark.org/0.31.2/#hard-line-breaks
+trim_trailing_whitespace = false

Filelist

@@ -18,6 +18,7 @@ SRC_ALL =	\
 		.hgignore \
 		.appveyor.yml \
 		.codecov.yml \
+		.editorconfig \
 		ci/appveyor.bat \
 		ci/config.mk*.sed \
 		ci/if_ver*.vim \

runtime/doc/develop.txt

@@ -1,4 +1,4 @@
-*develop.txt*   For Vim version 9.1.  Last change: 2024 Oct 31
+*develop.txt*   For Vim version 9.1.  Last change: 2024 Nov 11
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -166,6 +166,10 @@ stick to these rules, to keep the sources readable and maintainable.
 
 This list is not complete.  Look in the source code for more examples.
 
+The code repository contains an editorconfig file, that can be used together
+with the distributed editorconfig plugin |editorconfig-install| to ensure the
+recommended style is followed.
+
 
 MAKING CHANGES						*style-changes*