sagemathgh-36919: refresh the doc about coercion and test the given example
    
There is one example of ring in the doc about coercion.

Currently not tested and very much using old-style.

So let's refresh it and test it.

### 📝 Checklist

- [x] The title is concise, informative, and self-explanatory.
- [x] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [x] I have created tests covering the changes.
- [x] I have updated the documentation accordingly.
    
URL: sagemath#36919
Reported by: Frédéric Chapoton
Reviewer(s): Ruchit Jagodara

sagemathgh-37262: Added automatic size labeler
    
I have implemented the `automatic size labeler`, which now assigns
labels to pull requests based on the number of lines changed

**Minimal**
Typically involves very small changes, bug fixes, or updates that
require only a few lines of code, often less than 50.
sagemath#37208 sagemath#37146 sagemath#37043

**Small**
Involves more substantial changes than minimal, potentially adding new
features or making modifications to existing ones. The range is usually
between 50 to 100 lines of code.
sagemath#37152 sagemath#37132

**Moderate**
Represents a significant portion of the codebase being modified, such as
adding new features, refactoring, or making extensive changes to
existing functionalities. This might involve between 100 to 300 lines of
code.
sagemath#36919 sagemath#37112

**Large**
Involves substantial and complex changes across various parts of the
codebase. This could include major architectural changes, the
introduction of new modules, or a significant overhaul of existing
features, often exceeding 300 lines of code.
sagemath#37125 sagemath#36977 sagemath#36972

### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->
<!-- If your change requires a documentation PR, please link it
appropriately -->
<!-- If you're unsure about any of these, don't hesitate to ask. We're
here to help! -->
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- [x] The title is concise, informative, and self-explanatory.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.

Fixes: sagemath#37254
    
URL: sagemath#37262
Reported by: Aman Moon
Reviewer(s): Sebastian Oehms

sagemathgh-37262: Added automatic size labeler
    
I have implemented the `automatic size labeler`, which now assigns
labels to pull requests based on the number of lines changed

**Minimal**
Typically involves very small changes, bug fixes, or updates that
require only a few lines of code, often less than 50.
sagemath#37208 sagemath#37146 sagemath#37043

**Small**
Involves more substantial changes than minimal, potentially adding new
features or making modifications to existing ones. The range is usually
between 50 to 100 lines of code.
sagemath#37152 sagemath#37132

**Moderate**
Represents a significant portion of the codebase being modified, such as
adding new features, refactoring, or making extensive changes to
existing functionalities. This might involve between 100 to 300 lines of
code.
sagemath#36919 sagemath#37112

**Large**
Involves substantial and complex changes across various parts of the
codebase. This could include major architectural changes, the
introduction of new modules, or a significant overhaul of existing
features, often exceeding 300 lines of code.
sagemath#37125 sagemath#36977 sagemath#36972

### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->
<!-- If your change requires a documentation PR, please link it
appropriately -->
<!-- If you're unsure about any of these, don't hesitate to ask. We're
here to help! -->
<!-- Feel free to remove irrelevant items. -->

- [x] The title is concise, informative, and self-explanatory.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.

Fixes: sagemath#37254
    
URL: sagemath#37262
Reported by: Aman Moon
Reviewer(s): Sebastian Oehms

sagemathgh-37262: Added automatic size labeler
    
I have implemented the `automatic size labeler`, which now assigns
labels to pull requests based on the number of lines changed

**Minimal**
Typically involves very small changes, bug fixes, or updates that
require only a few lines of code, often less than 50.
sagemath#37208 sagemath#37146 sagemath#37043

**Small**
Involves more substantial changes than minimal, potentially adding new
features or making modifications to existing ones. The range is usually
between 50 to 100 lines of code.
sagemath#37152 sagemath#37132

**Moderate**
Represents a significant portion of the codebase being modified, such as
adding new features, refactoring, or making extensive changes to
existing functionalities. This might involve between 100 to 300 lines of
code.
sagemath#36919 sagemath#37112

**Large**
Involves substantial and complex changes across various parts of the
codebase. This could include major architectural changes, the
introduction of new modules, or a significant overhaul of existing
features, often exceeding 300 lines of code.
sagemath#37125 sagemath#36977 sagemath#36972

### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->
<!-- If your change requires a documentation PR, please link it
appropriately -->
<!-- If you're unsure about any of these, don't hesitate to ask. We're
here to help! -->
<!-- Feel free to remove irrelevant items. -->

- [x] The title is concise, informative, and self-explanatory.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.

Fixes: sagemath#37254
    
URL: sagemath#37262
Reported by: Aman Moon
Reviewer(s): Sebastian Oehms