Create Obsidian plugin for Khoj

- Features
  - Search using Khoj from within the Obsidian app
    Allow Natural language search on your (markdown) notes in Obsidian Vault

  - Show search results as rendered (instead of raw) Markdown
    Improve legibility of the results

  - Jump to selected note from search result in Khoj search modal
    Simplify seeing result within its original note context

  - Automatically configure khoj to index markdown files in current vault
    Reduce khoj setup steps for plugin users by using reasonable defaults

    - Code updates the markdown config in khoj.yml and triggers index update
    - It can be configured by user in khoj plugin settings, if required

  - Add Demo and detailed Readme for the Obsidian plugin
    Ease setup and usage. Give context about capabilities

- Miscellaneous
  - Trying keep a mono repo until the Khoj project is mature enough
    to reduce maintainance burden

src/interface/obsidian/README.md

@@ -0,0 +1,98 @@
+# Khoj Obsidian 🦅
+> Natural language search for your Obsidian notes using [Khoj](https://github.com/debanjum/khoj)
+
+## Table of Contents
+
+- [Features](#Features)
+- [Demo](#Demo)
+  - [Description](#Description)
+  - [Interface](#Interface)
+- [Setup](#Setup)
+  - [Setup Backend](#1-Setup-Backend)
+  - [Setup Plugin](#2-Setup-Plugin)
+- [Use](#Use)
+  - [Query Filters](#Query-filters)
+- [Upgrade](#Upgrade)
+  - [Upgrade Backend](#1-Upgrade-Backend)
+  - [Upgrade Plugin](#2-Upgrade-Plugin)
+- [Troubleshoot](#Troubleshoot)
+- [Implementation](#Implementation)
+
+## Features
+- **Natural**: Advanced natural language understanding using Transformer based ML Models
+- **Local**: Your personal data stays local. All search, indexing is done on your machine[\*](https://github.com/debanjum/khoj#miscellaneous)
+- **Incremental**: Incremental search for a fast, search-as-you-type experience
+
+## Demo
+https://user-images.githubusercontent.com/6413477/210486007-36ee3407-e6aa-4185-8a26-b0bfc0a4344f.mp4
+
+### Description
+1. Install Khoj via `pip` and start Khoj backend in non-gui mode
+2. Install Khoj plugin via Community Plugins settings pane on Obsidian app
+3. Check the new Khoj plugin settings
+4. Let Khoj backend index the markdown files in the current Vault
+5. Open Khoj plugin on Obsidian via Search button on Left Pane
+6. Search \"*Announce plugin to folks*\" in the [Obsidian Plugin docs](https://marcus.se.net/obsidian-plugin-docs/)
+7. Jump to the [search result](https://marcus.se.net/obsidian-plugin-docs/publishing/submit-your-plugin)
+
+### Interface
+![](https://github.com/debanjum/khoj/blob/master/src/interface/obsidian/docs/khoj_obsidian_screenshot_0.1.0.png)
+
+## Setup
+### 1. Setup Backend
+
+```shell
+pip install khoj-assistant && khoj --no-gui
+```
+## 2. Setup Plugin
+  1. Open *Community plugins* tab in Obsidian settings panel
+  2. Click Browse and Search for *Khoj*
+  3. Click *Install*, after that click *Enable* on the Khoj plugin
+
+See [official docs](https://help.obsidian.md/Advanced+topics/Community+plugins#Discover+and+install+community+plugins) for details
+
+## Use
+Click the *Khoj search icon* 🔎 on the [Ribbon](https://help.obsidian.md/User+interface/Workspace/Ribbon) or Search for *Khoj: Search* in the [Command Palette](https://help.obsidian.md/Plugins/Command+palette)
+
+### 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
+### 1. Upgrade Backend
+  ```shell
+  pip install --upgrade khoj-assistant
+  ```
+### 2. Upgrade Plugin
+  1. Open *Community plugins* tab in Obsidian settings
+  2. Click the *Check for updates* button
+  3. Click the *Update* button next to Khoj, if available
+
+## Troubleshooting
+  1. Open the Khoj plugin settings pane, in case you need to configure Khoj
+  2. Toggle Enable/Disable Khoj, in case settings changes have not applied
+
+## Implementation
+The plugin implements the following functionality to search your notes with Khoj:
+- [X] Open the Khoj search modal via left ribbon icon or the *Khoj: Search* command
+- [X] Render results as Markdown preview to improve readability
+- [X] Configure Khoj via the plugin setting tab on the settings page
+  - Set Obsidian Vault to Index with Khoj. Defaults to all markdown files in current Vault
+  - Set URL of Khoj backend
+  - Set Number of Search Results to show in Search Modal
+- [ ] Allow user to trigger reranking of result to improve search quality