Update documentation usage examples in build scripts

Author: braboj

.scripts/gen_markdown_chapters.py

@@ -2,7 +2,7 @@
 """Generate aggregated Markdown files for each examples subfolder.
 
 Usage:
-    python .scripts/examples_to_markdown_files.py \
+    python .scripts/gen_markdown_chapters.py \
         --examples-dir examples \
         --output-dir docs
 

.scripts/gen_markdown_pages.py

@@ -2,7 +2,7 @@
 """Generate a Markdown file for each Python example.
 
 Usage:
-    python .scripts/examples_to_markdown_files.py \
+    python .scripts/gen_markdown_pages.py \
         --examples-dir examples \
         --template templates/example_file.mustache \
         --output-dir docs

.scripts/gen_single_markdown.py

@@ -2,7 +2,7 @@
 """Generate a Markdown page from Python example files.
 
 Usage::
-    python .scripts/examples_to_markdown.py \
+    python .scripts/gen_single_markdown.py \
         --examples-dir examples \
         --template templates/examples_page.mustache \
         --output examples.md