pyproject: Update description to use consistent branding for pdfRest

- Changed all references of "PDFRest" to "pdfRest" in `pyproject.toml` and
  `mkdocs.yml` to align with branding guidelines.

Assisted-by: Codex

Author: datalogics-kam

mkdocs.yml

@@ -1,5 +1,5 @@
 site_name: pdfrest
-site_description: Python client library for interacting with the PDFRest API
+site_description: Python client library for interacting with the pdfRest API
 repo_url: https://github.com/pdfrest/pdfrest-python
 docs_dir: docs
 site_dir: site

pyproject.toml

@@ -1,7 +1,7 @@
 [project]
 name = "pdfrest"
 version = "1.0.2"
-description = "Python client library for interacting with the PDFRest API"
+description = "Python client library for interacting with the pdfRest API"
 readme = {file = "README.md", content-type = "text/markdown"}
 authors = [
     {name = "Datalogics"},