docs: how to use editor and contribute maps

Author: asdofindia

README.md

@@ -2,6 +2,42 @@
 
 This is a global repository to hold community curated maps to convert from ASCII to Unicode.
 
+## How to use this
+
+The maps inside [maps directory](https://github.com/libindic/unicode-conversion-maps/tree/main/maps) are used in various utilities like [Payyans](https://libindic.org/Payyans), [Freaknz](https://gitlab.com/kannanvm/freaknz-qt/), [Chekkans](http://asdofindia.github.io/chekkans-web/), etc. These maps are all community maintained. In the near future, this repository will be used to supply maps to all of these projects and more.
+
+### Editor
+
+If you like to edit maps, you can use the [editor](https://libindic.github.io/unicode-conversion-maps/editor/). In editor, you have to choose the font file and map file. Once loaded, these are opened in the tables at the bottom.
+
+![](https://i.imgur.com/FUo37cL.png)
+
+Each glyph and its mapping are loaded in the following format:
+
+```
+--------------
+| A  B       |
+| C      D   |
+|        E   |
+-------------
+```
+
+Explanation of these:
+
+* A - the unicode decimal point.
+* B - extended ASCII character that forms the left hand side of the maps
+* C - the glyph in the font at that code point (if it exists)
+* D - The input box where the currently mapped character is loaded (should be same as C). If B and C are the same, this can be omitted.
+* E - The Unicode codepoint of D.
+
+After changing the mapping (by editing D) for all glyphs, you can copy the mapping from the textarea in the top right of the page.
+
+### Using map
+
+You can contribute the map to the community by either editing an existing map or by [creating a new map ](https://github.com/libindic/unicode-conversion-maps/new/main/maps).
+
+If you want to directly use these maps, you can paste them in [chekkans-web](http://asdofindia.github.io/chekkans-web/) at the bottom and use it directly.
+
 ## History
 
 * [Payyans](https://github.com/libindic/payyans) is the origin of a lot of map files.