Fix minor typos in unicode.rst

[manoj-km24]

This PR fixes minor typos in Doc/c-api/unicode.rst. Fixes the below statement:

The return type is now ``const char *`` rather of ``char *``

as

The return type is now ``const char *`` rather than ``char *``

Also makes the word "written character" as "written characters" in:

Return the number of written character, or return ``-1`` and raise an
exception on error.

[read-the-docs-community]

Documentation build overview

📚 cpython-previews | 🛠️ Build #32612555 | 📁 Comparing 469f171 against main (354ef33)

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1 file changed

± c-api/unicode.html

[miss-islington-app]

Thanks @manoj-km24 for the PR, and @JelleZijlstra for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14, 3.15.
🐍🍒⛏🤖

[bedevere-app]

GH-149620 is a backport of this pull request to the 3.15 branch.

[miss-islington-app]

Sorry, @manoj-km24 and @JelleZijlstra, I could not cleanly backport this to 3.13 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 4e97ff3351f381a61b238bd8e805e4e8dd3ea5cf 3.13

[bedevere-app]

GH-149621 is a backport of this pull request to the 3.14 branch.