Add Filtres API documentation with usage examples and filter syntax

Author: tacxou

docs/Filtres_API.md

@@ -0,0 +1,35 @@
+# Filtres API
+
+## Usages
+### Filters
+#### Syntax
+`filters[PREFIX + FIELD]=SEARCH`
+#### Example
+`filters[=subject]=53`
+subject field equal to 53
+#### Usage
+```bash
+curl --request GET \
+  --url 'http://localhost/search?limit=9999&filters%5B%5Esequence%5D=%2F53%2F&sort%5Bmetadata.createdAt%5D=-1&sort%5Bsubject%5D=1'
+  
+# limit=9999
+# filters[^sequence]=/53/
+# sort[metadata.createdAt]=-1
+# sort[subject]=1
+```
+#### List
+| Filter | Description           |
+|--------|-----------------------|
+| :      | Equal                 |
+| #      | Number Equal          |
+| !#     | Number Not Equal      |
+| !:     | Not Equal             |
+| \>     | Greater Than          |
+| \>|    | Greater Than or Equal |
+| \<     | Less Than             |
+| \<|    | Less Than or Equal    |
+| @      | in                    |
+| !@     | not in                |
+| @#     | number in             |
+| !@#    | number not in         |
+| \^     | regex                 |