Fix errata in documentation

This patch addresses the following errata found in the project documentation:

* Common typos.
* Missing use of trademarks.
* Incomplete operator descriptions.
* Examples of code that have since been removed from the library.
* Plus clarification over the usage of `All` category for data types and layouts.

In addition, the Operator list was not generated properly due to:

* Non-matching cases in the filenames (i.e. `Elementwise` and `ElementWise`). For consistency, all usages of the latter have been renamed to the former.
* Extra data layout tables in the headers for the `NESlice` and `NEStridedSlice` functions (note: not present in CL counterpart) meant documentation for those functions was generated twice.

Resolves: COMPMID-4561, COMPMID-4562, COMPMID-4563
Change-Id: I1eb24559545397749e636ffbf927727fb1bc6201
Signed-off-by: Jakub Sujak <jakub.sujak@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/5769
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Sheri Zhang <sheri.zhang@arm.com>
Reviewed-by: SiCong Li <sicong.li@arm.com>
diff --git a/docs/user_guide/data_layout.dox b/docs/user_guide/data_layout.dox
index 48f15ac..97d3ea6 100644
--- a/docs/user_guide/data_layout.dox
+++ b/docs/user_guide/data_layout.dox
@@ -29,7 +29,7 @@
 
 @section data_layout_support_supported_data_layout Supported Data Layouts
 
-Compute Library supports the follwing data layouts and
+Compute Library supports the following data layouts and
 the right-most letter represents the fastest changing dimension:
 
 - NHWC: The native layout of Compute Library that delivers the best performance where channels are in the fastest changing dimension