DS-15484: Document upcoming SQL feature additions to Workers Analytics Engine (#25446)

* DS-15484: Document upcoming SQL feature additions to WAE

This PR adds documentation for various SQL feature additions to Workers Analytics
Engine done in RM-24208.

There are now too many functions to sensibly put in a single page, so I've broken
the SQL Reference documentation out into a page structure which is extensible.

I've taken deliberate inspiration from the ClickHouse SQL documentation page
structure [1]. WAE's SQL dialect is based on the ClickHouse SQL dialect, and we
intend to gradually add more and more functions from CH SQL. Having a similar docs
structure will work well for that.

[1] https://clickhouse.com/docs/sql-reference/functions/math-functions

* DS-15484: Label new functions with `New` badges

This was suggested by product.

There's some functions which have slightly changed (e.g. `quantileExactWeighted`) to support
a new alternate form more like ClickHouse. I've not labelled those functions because it's
not so important to existing users.

* Merge rounding functions into mathematical functions page

* Review suggestions

* Document topK and topKWeighted

* Remaining review suggestions

Author: 46bit

src/content/docs/analytics/analytics-engine/sampling.mdx

@@ -70,7 +70,7 @@ Here are some examples of how to express some common queries over sampled data.
 | Count events in a dataset          | `count()`                | `sum(_sample_interval)`                                 |
 | Sum a quantity, for example, bytes | `sum(bytes)`             | `sum(bytes * _sample_interval)`                         |
 | Average a quantity                 | `avg(bytes)`             | `sum(bytes * _sample_interval) / sum(_sample_interval)` |
-| Compute quantiles                  | `quantile(0.50)(bytes)`  | `quantileWeighted(0.50)(bytes, _sample_interval)`       |
+| Compute quantiles                  | `quantile(0.50)(bytes)`  | `quantileExactWeighted(0.50)(bytes, _sample_interval)`  |
 
 Note that the accuracy of results is not determined by the sample interval, similar to the mapping analogy mentioned earlier. A high sample interval can still provide precise results. Instead, accuracy depends on the total number of data points queried and their distribution.
 

src/content/docs/analytics/analytics-engine/sql-api.mdx

@@ -32,7 +32,7 @@ Use the dashboard to create a token with permission to read analytics data on yo
 
 ## Querying the API
 
-Submit the query text in the body of a `POST` request to the API address. The format of the data returned can be selected using the [`FORMAT` option](/analytics/analytics-engine/sql-reference/#format-clause) in your query.
+Submit the query text in the body of a `POST` request to the API address. The format of the data returned can be selected using the [`FORMAT`](/analytics/analytics-engine/sql-reference/statements/#format-clause) option in your query.
 
 You can use cURL to test the API as follows, replacing the `<account_id>` with your 32 character account ID (available in the dashboard) and the `<token>` with the token string you generated above.
 
@@ -82,7 +82,7 @@ The rate at which the data is sampled is exposed via the `_sample_interval` colu
 | `SELECT SUM(double1) FROM ...` | `SELECT SUM(_sample_interval * double1) FROM ...`                         |
 | `SELECT AVG(double1) FROM ...` | `SELECT SUM(_sample_interval * double1) / SUM(_sample_interval) FROM ...` |
 
-Additionally, the [QUANTILEWEIGHTED function](/analytics/analytics-engine/sql-reference/#quantileweighted) is designed to be used with sample interval as the third argument.
+Additionally, the [QUANTILEEXACTWEIGHTED](/analytics/analytics-engine/sql-reference/aggregate-functions/#quantileexactweighted) function is designed to be used with sample interval as the third argument.
 
 ## Example queries