docs: Add how to install Pydantic without binaries

Pydantic can be installed without binary files. This significantly
reduces the additional size it adds to the compressed Lambda packages
(down to 2MB from 25MB) at the expense of 30%-50% of its performance.

While at it I also updated the amount of megabyte Pydantic adds to the
package, as it wasn't clear if the stated number referred to compressed
or uncompressed package size and I couldn't reproduce the 75MB either
way.

docs/utilities/parser.md

@@ -14,7 +14,13 @@ This utility provides data parsing and deep validation using [Pydantic](https://
 **Extra dependency**
 
 ???+ warning
-    This will increase the overall package size by approximately 75MB due to Pydantic dependency.
+
+    This will increase the compressed package size by approximately 25MB due to the Pydantic dependency.
+
+    To reduce the impact on the package size at the expense of 30%-50% of its performance [Pydantic can also be
+    installed without binary files](https://pydantic-docs.helpmanual.io/install/#performance-vs-package-size-trade-off):
+
+    `SKIP_CYTHON=1 pip install --no-binary pydantic aws-lambda-powertools[pydantic]`
 
 Install parser's extra dependencies using **`pip install aws-lambda-powertools[pydantic]`**.