docs: feat: Write the flavors section of the README

Signed-off-by: 林博仁(Buo-ren, Lin) <Buo.Ren.Lin@gmail.com>

README.md

@@ -5,6 +5,29 @@ Ready-to-use bash shell script templates at your fingertips!
 <https://gitlab.com/the-common/bash-script-templates>  
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+## Flavors
+
+This product provides several _flavors_ of the Bash script template to satisfy different needs:
+
+### [PRIMITIVE](primitive.sh)
+
+The considered to be the bare-minimum for bash scripting:
+
+* Shebang/Hashbang file header
+* Script description and copyright declaration header
+* Defensive interpreter behavior settings
+
+### [BASIC](basic.sh)
+
+Inherited from the [PRIMITIVE](#primitive) flavor, but with the following additions:
+
+* Runtime dependency detection(check whether all the required commands are available from the command search PATHs
+* The following convenience variable definitions:
+    + `script`: The absolute path of the shell script
+    + `script_dir`: The absolute path of the directory that contains the shell script
+    + `script_filename`: The full filename of the shell script
+    + `script_name`: The name of the shellscript, excluding the filename suffixes
+
 ## References
 
 * [The Common / The Common GNU Bash Shell Script Templates · GitLab](https://gitlab.com/the-common/bash-script-templates)