docs(cdk/table): document fixedLayout and recycleRows (#21926)

src/cdk/table/table.md

@@ -135,6 +135,18 @@ updates. This can be based on _anything_: websocket connections, user interactio
 time-based intervals, etc. Most commonly, updates will be triggered by user interactions like
 sorting and pagination.
 
+##### `fixedLayout`
+The CDK table measures the dimensions of sticky elements before applying the styles that make them
+"stick". Because native tables derive column widths from the content within each cell, these
+dimensions are re-checked when the underlying data changes.
+
+Enabling `fixedLayout` will enforce uniform column widths, so the table can reliably cache and reuse
+them when calculating sticky styles. This can reduce rendering latency for large native tables.
+
+```html
+<table cdk-table [dataSource]="dataSource" fixedLayout>
+```
+
 ##### `trackBy`
 
 To improve performance, a `trackBy` function can be provided to the table similar to Angular’s
@@ -145,6 +157,16 @@ table how to uniquely identify rows to track how the data changes with each upda
 <table cdk-table [dataSource]="dataSource" [trackBy]="myTrackById">
 ```
 
+##### `recycleRows`
+By default, `CdkTable` creates and destroys an internal Angular view for each row. This allows rows 
+to participate in animations and to toggle between different row templates with `cdkRowDefWhen`. If 
+you don't need these features, you can instruct the table to cache and recycle rows by specifying 
+`recycleRows`.
+
+```html
+<table cdk-table [dataSource]="dataSource" recycleRows>
+```
+
 ### Alternate HTML to using native table
 
 The CDK table does not require that you use a native HTML table. If you want to have full control