Document using Word, Date and File Query Filter in Readme

Readme.md

@@ -18,6 +18,8 @@
   - [Configure](#2-Configure)
   - [Run](#3-Run)
 - [Use](#Use)
+  - [Interfaces](#Interfaces-1)
+  - [Query Filters](#Query-filters)
 - [Upgrade](#Upgrade)
 - [Troubleshoot](#Troubleshoot)
 - [Miscellaneous](#Miscellaneous)
@@ -88,6 +90,7 @@ khoj
 2. Click `Configure` and wait. The app will download ML models and index the content for search
 
 ## Use
+### Interfaces
 
 - **Khoj via Web**
   - Open <http://localhost:8000/> via desktop interface or directly
@@ -97,6 +100,25 @@ khoj
 - **Khoj via API**
   - See the Khoj FastAPI [Swagger Docs](http://localhost:8000/docs), [ReDocs](http://localhost:8000/redocs)
 
+### Query Filters
+Use structured query syntax to filter the natural language search results
+- **Word Filter**: Get entries that include/exclude a specified term
+  - Entries that contain term_to_include: `+"term_to_include"`
+  - Entries that contain term_to_exclude: `-"term_to_exclude"`
+- **Date Filter**: Get entries containing dates in YYYY-MM-DD format from specified date (range)
+  - Entries from April 1st 1984: `dt:"1984-04-01"`
+  - Entries after March 31st 1984: `dt>="1984-04-01"`
+  - Entries before April 2nd 1984 : `dt<="1984-04-01"`
+- **File Filter**: Get entries from a specified file
+  - Entries from incoming.org file: `file:"incoming.org"`
+- Combined Example
+  - `what is the meaning of life? file:"1984.org" dt>="1984-01-01" dt<="1985-01-01" -"big" -"brother"`
+  - Adds all filters to the natural language query. It should return entries
+    - from the file *1984.org*
+    - containing dates from the year *1984*
+    - excluding words *"big"* and *"brother"*
+    - that best match the natural language query *"what is the meaning of life?"*
+
 ## Upgrade
 
 ```shell