docs: Add keyword classifier configuration guide (vllm-project#559)

* docs: Add keyword classifier configuration guide

- Created website/docs/overview/categories/keyword-configuration.md for keyword-based classification rules.
- Detailed configuration structure, parameters, and examples.
- Updated website/docs/overview/categories/configuration.md with a link to the new guide.
- Modified website/sidebars.ts to integrate the new page into the sidebar.

Signed-off-by: Srinivas A <[email protected]>

* refactor: Fix pre-commit

- Fix indentation in keyword-configuration.md

Signed-off-by: Srinivas A <[email protected]>

---------

Signed-off-by: Srinivas A <[email protected]>

Author: srini-abhiram

website/docs/overview/categories/configuration.md

@@ -613,5 +613,6 @@ categories:
 ## Next Steps
 
 - [**Supported Categories**](supported-categories.md) - Review all available categories
+- [**Keyword Classifier Configuration**](keyword-configuration.md) - Learn how to configure keyword-based routing rules
 - [**Technical Details**](technical-details.md) - Understand the implementation
 - [**Category Overview**](overview.md) - Learn about the category system

website/docs/overview/categories/keyword-configuration.md

@@ -0,0 +1,77 @@
+---
+sidebar_label: Keyword Classifier Configuration
+---
+
+# Keyword Classifier Configuration
+
+The Keyword Classifier allows you to define custom routing rules based on the presence or absence of specific keywords or regular expressions within the input text. This provides a flexible and powerful way to categorize and route requests without relying solely on machine learning models.
+
+## Configuration Structure
+
+Keyword classification rules are defined in the `config.yaml` file under the `classifier.keyword_rules` section. Each rule is an object with the following parameters:
+
+```yaml
+classifier:
+  keyword_rules:
+    - category: "category_name"
+      operator: "AND" | "OR" | "NOR"
+      keywords: ["keyword1", "keyword2"]
+      case_sensitive: true | false
+```
+
+## Configuration Parameters
+
+### `category` (Required)
+
+- **Type**: String
+- **Description**: The classification label to assign if this rule matches. This will be the `category` returned by the classifier.
+- **Example**: `"urgent_request"`, `"sensitive_data"`
+
+### `operator` (Required)
+
+- **Type**: String
+- **Description**: Defines how multiple keywords within this rule are combined to determine a match.
+- **Valid Values**:
+  - `AND`: All keywords in the `keywords` list must be present in the input text for the rule to match.
+  - `OR`: At least one keyword from the `keywords` list must be present in the input text for the rule to match.
+  - `NOR`: None of the keywords from the `keywords` list must be present in the input text for the rule to match.
+- **Example**: `"OR"`, `"AND"`, `"NOR"`
+
+### `keywords` (Required)
+
+- **Type**: Array of Strings
+- **Description**: A list of strings that the classifier will search for in the input text. These strings are treated as regular expressions.
+- **Behavior**:
+  - For robustness and to allow for special characters, all keywords are automatically escaped using `regexp.QuoteMeta` before being compiled into regular expressions. This means you can use special regex characters (like `.`, `*`, `+`) as literal characters in your keywords without needing to escape them yourself in the `config.yaml`.
+  - Word boundaries (`\b`) are conditionally applied around keywords that contain word characters. This helps ensure whole-word matching where appropriate (e.g., "cat" matches "cat" but not "category"). Keywords consisting solely of non-word characters (like punctuation) will not have word boundaries applied.
+- **Example**: `["urgent", "immediate", "asap"]`, `["SSN", "social security number"]`, `["user\\.name@domain\\.com", "C:\\Program Files\\\\"]`
+
+### `case_sensitive` (Optional)
+
+- **Type**: Boolean
+- **Description**: Determines whether the keyword matching should be case-sensitive.
+- **Default**: `false` (case-insensitive)
+- **Example**: `true`
+
+## Complete Configuration Example
+
+```yaml
+classifier:
+  keyword_rules:
+    - category: "urgent_request"
+      operator: "OR"
+      keywords: ["urgent", "immediate", "asap"]
+      case_sensitive: false
+    - category: "sensitive_data"
+      operator: "AND"
+      keywords: ["SSN", "social security number", "credit card"]
+      case_sensitive: false
+    - category: "exclude_spam"
+      operator: "NOR"
+      keywords: ["buy now", "free money"]
+      case_sensitive: false
+    - category: "regex_pattern_match"
+      operator: "OR"
+      keywords: ["user\\.name@domain\\.com", "C:\\Program Files\\\\"] # Keywords are treated as regex
+      case_sensitive: false
+```

website/sidebars.ts

@@ -38,6 +38,7 @@ const sidebars: SidebarsConfig = {
             'overview/categories/overview',
             'overview/categories/supported-categories',
             'overview/categories/configuration',
+            'overview/categories/keyword-configuration',
             'overview/categories/technical-details',
           ],
         },