docs: update

README.md

@@ -70,6 +70,7 @@ See something incorrectly described, buggy or outright wrong? Open an issue or s
     * [Miscellaneous](#miscellaneous)
 * [ARITHMETIC](#arithmetic-1)
     * [Ternary Tests](#ternary-tests)
+    * [Check if a number is a float](#check-if-a-number-is-a-float)
 * [TRAPS](#traps)
     * [Do something on script exit](#do-something-on-script-exit)
     * [Ignore terminal interrupt (CTRL+C, SIGINT)](#ignore-terminal-interrupt-ctrlc-sigint)
@@ -802,6 +803,32 @@ For use in `[ ]` `if [ ]; then` and `test`.
 var=$((var2 > var ? var2 : var))
 ```
 
+## Check if a number is a float
+
+**Example Function:**
+
+```sh
+is_float() {
+    # Usage: is_float "number"
+    case $1 in
+        *.*.*|*[!-.0-9]*) ;;
+        *[0-9].[0-9]*) return 0
+    esac
+
+    return 1
+}
+```
+
+**Example Usage:**
+
+```shell
+$ is_float 1.1 && echo true
+true
+
+$ is_float 1 && echo true
+$
+```
+
 # TRAPS
 
 Traps allow a script to execute code on various signals. In [pxltrm](https://github.com/dylanaraps/pxltrm) (*a pixel art editor written in bash*)  traps are used to redraw the user interface on window resize. Another use case is cleaning up temporary files on script exit.