Update free-programming-books-langs.md (#13139)

Add the official Python documentation tutorial (docs.python.org/es/3/tutorial/)
to the Spanish Python section. This is the official tutorial maintained by
the Python Software Foundation and translated by the python-docs-es community.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

books/free-programming-books-da.md

@@ -25,11 +25,6 @@
 * [Notes about C++](http://people.cs.aau.dk/~normark/ap/index.html) - Kurt Nørmark (HTML)
 
 
-### Delphi
-
-* [Programmering Med Delphi 7](http://olewitthansen.dk/Datalogi/ProgrammeringMedDelphi.pdf) - Ole Witt-Hansen (PDF)
-
-
 ### Java
 
 * [Objektorienteret programmering i Java](http://javabog.dk) - Jacob Nordfalk

books/free-programming-books-es.md

@@ -344,6 +344,7 @@
 * [Aprende Python](https://aprendepython.es) - Sergio Delgado Quintero (HTML, PDF) (CC BY)
 * [Aprendiendo a Programar en Python con mi Computador](https://openlibra.com/en/book/download/aprendiendo-a-programar-en-python-con-mi-computador) (PDF)
 * [Doma de Serpientes para Niños: Aprendiendo a Programar con Python](http://code.google.com/p/swfk-es/) (HTML)
+* [El tutorial de Python](https://docs.python.org/es/3/tutorial/) - Python Software Foundation (HTML)
 * [Inmersión en Python](https://code.google.com/archive/p/inmersionenpython3/) (HTML)
 * [Inmersión en Python 3](https://storage.googleapis.com/google-code-archive-downloads/v2/code.google.com/inmersionenpython3/inmersionEnPython3.0.11.pdf) - Mark Pilgrim, `trl.:` José Miguel González Aguilera (PDF) (descarga directa)
 * [Introducción a la programación con Python](http://repositori.uji.es/xmlui/bitstream/handle/10234/24305/s23.pdf) - Andrés Marzal, Isabel Gracia (PDF)

books/free-programming-books-langs.md

@@ -533,7 +533,7 @@ Books on general-purpose programming that don't focus on a specific language are
 * [C++ Succinctly, Syncfusion](https://www.syncfusion.com/resources/techportal/ebooks/cplusplus) (PDF, Kindle) (email address *requested*, not required)
 * [C++ Tricks](http://www.bordoon.com/cplusplus/book_wrapper.html)
 * [C++ Tutorial](https://www.cprogramming.com/tutorial/c++-tutorial.html) - Alex Allain
-* [CS106X Programming Abstractions in C++](http://web.stanford.edu/class/cs106x/)
+* [CS106X Programming Abstractions in C++](https://web.stanford.edu/class/cs106x/)
 * [Elements of Programming](http://elementsofprogramming.com) - Alexander Stepanov, Paul McJones (PDF)
 * [Essential C++](https://www.programming-books.io/essential/cpp/) - Krzysztof Kowalczyk, StackOverflow Contributors (CC BY-SA)
 * [Financial Numerical Recipes in C++](https://ba-odegaard.no/gcc_prog/recipes/) - Bernt Arne Ødegaard (PDF)
@@ -1906,6 +1906,7 @@ Books on general-purpose programming that don't focus on a specific language are
 ### PostgreSQL
 
 * [Essential PostgreSQL](https://www.programming-books.io/essential/postgresql/) - Krzysztof Kowalczyk, StackOverflow Contributors
+* [Lift the Elephant: Scaling PostgreSQL Beyond Query Optimization](https://leanpub.com/lift-the-elephant) - Alex Yarotsky (PDF) *(Leanpub account or valid email requested)*
 * [Postgres Official Documentation](http://www.postgresql.org/docs/)
 * [Postgres Succinctly](https://www.syncfusion.com/resources/techportal/ebooks/postgres) (PDF, Kindle) (email address *requested*, not required)
 * [PostgreSQL Notes for Professionals](https://goalkicker.com/PostgreSQLBook/) - Compiled from StackOverflow documentation (PDF)