Add regex patterns

Added regex patterns and other misc updates to improve usability

www/docs/api-reference/search-apis/interpreting-responses/metadata.md

@@ -12,7 +12,9 @@ In <Config v="names.product"/>, when you [index a document](/docs/api-reference/
 document has a `type` parameter that determines the format of the document 
 as `core` or `structured`. The `core` type has `document_parts` and the `structured` 
 type has `sections`. Both can be nested and both can contain separate `metadata`, 
-including some metadata that <Config v="names.product"/> will auto-generate. 
+including some metadata that <Config v="names.product"/> will auto-generate.
+
+## Metadata structure
 
 For example, a document might have global attributes such as the `URL` or `owner` 
 but individual sections have a `section` attribute and a `lang`.
@@ -65,17 +67,83 @@ document-level metadata, which can reduce the total time for the response.
 
 ## Metadata type consistency
 
-The metadata type conversion applies only to the query responses. Metadata 
-remains unconverted during the document upload process, even when using API v2: 
+The metadata type conversion applies only to the `part_metadata` and 
+`document_metadata` fields in query responses. Metadata remains 
+unconverted during the document upload process, even when using API v2:
 
 * **Numbers** are returned as numbers (for example, `section: 2`, `publicationyear: 1979`).
-* **Booleans** are returned as booleans.
+* **Booleans** are returned as `true` or `false` (case-sensitive).
 * **JSON objects** maintain their native structure.
 
 This behavior differs from API v1, where metadata such as `section` or 
 `publicationyear` might have been returned as strings (`"2"`, `"1979"`). 
 Ensure client applications handle these types correctly for smooth integration. 
 
+## Metadata type regex patterns
+
+The following regex examples provide information about how each type is 
+identified and processed. By understanding these patterns, users can account 
+for type conversion in their client applications.
+
+### Numbers regex
+
+This pattern matches valid numeric formats, including integers, decimals, and 
+scientific notation, ensuring they are returned as numbers instead of strings. 
+Examples include `section: 2` or `offset: 316`.
+
+**Pattern:** `-?(?:0|[1-9]\d*)(?:\.\d+)?(?:[eE][+-]?\d+)?`
+
+
+| Input      | Matches | Explanation                                |
+|------------|---------|--------------------------------------------|
+| `123`      | ✅  | Valid integer.                            |
+| `0`        | ✅  | Valid zero.                               |
+| `-456`     | ✅  | Valid negative integer.                   |
+| `3.14`     | ✅  | Valid decimal number.                     |
+| `-0.001`   | ✅  | Valid negative decimal.                   |
+| `2e10`     | ✅  | Valid scientific notation.                |
+| `-1.23E-4` | ✅  | Valid negative number in scientific notation. |
+| `.5`       | ❌  | Invalid (missing leading integer).        |
+| `1e`       | ❌  | Invalid (missing exponent value).         |
+| `1.2.3`    | ❌  | Invalid (multiple decimal points).        |
+| `-`        | ❌  | Invalid (missing digits).                 |
+
+
+### Boolean regex
+
+This pattern matches exact boolean values (`true` or `false`), with exact case 
+sensitivity and no extra characters.
+
+**Pattern:** `^(true|false)$`
+
+| Input      | Matches | Explanation                                     |
+|------------|---------|-------------------------------------------------|
+| `true`     | ✅  | Exact match for `true`.                        |
+| `false`    | ✅  | Exact match for `false`.                       |
+| ` true`    | ❌  | Invalid (leading space).                       |
+| `false `   | ❌  | Invalid (trailing space).                      |
+| `True`     | ❌  | Invalid (case-sensitive; must be lowercase).   |
+| `TRUE`     | ❌  | Invalid (case-sensitive; must be lowercase).   |
+| `falsey`   | ❌  | Invalid (extra characters after `false`).      |
+| `truest`   | ❌  | Invalid (extra characters after `true`).       |
+| `tru`      | ❌  | Invalid (partial match; incomplete `true`).    |
+
+### JSON regex
+
+This pattern identifies JSON-like structures, ensuring valid JSON objects so 
+that `{}` or arrays like `[]` are properly maintained.
+
+**Pattern:** `^[{|\[].*$`
+
+| Input         | Matches | Explanation                                  |
+|---------------|---------|----------------------------------------------|
+| `{example}`   | ✅  | Starts with `{` and has additional content.  |
+| `[data]`      | ✅  | Starts with `[` and has additional content.  |
+| `{`           | ✅  | Matches a single `{` at the start.           |
+| `[`           | ✅  | Matches a single `[` at the start.           |
+| `example`     | ❌  | Does not start with `{` or `[`.              |
+| `something{`  | ❌  | Starts with other characters, not `{`.       |
+| `(empty)`     | ❌  | Empty string does not match.                 |
 
 ## Combining document and section metadata
 

www/docs/learn/recommendation-systems/overview.md

@@ -46,7 +46,7 @@ are similar to the one they're looking at or a recently purchased product. These
 use cases can be dealt with by using <Config v="names.product"/> in a
 document-to-document search/recommendation platform.  In order to do this, the
 most important change is that you'll need to use `RESPONSE` similarity measure
-(available to [our Scale plan users](https://vectara.com/pricing/)).
+(available to [our Pro and Enterprise plan users](https://vectara.com/pricing/)).
 It's easier to explain how this is different by first explaining how the `DEFAULT`
 similarity works.