Expand stub to match other wiki entries

SC3059.md

@@ -1,3 +1,46 @@
-Case modification is not supported in dash and undefined in POSIX sh.
+## In POSIX sh, case modification is undefined.
 
-https://github.com/sbaudoin/sonar-shellcheck/blob/master/src/main/scripts/build_checks.yml
+(or "In dash, ... is not supported." when using `dash`)
+
+### Problematic code:
+
+```sh
+#!/bin/sh
+x='test'
+echo "${x^^[t]}"
+```
+
+### Correct code:
+
+The easiest solution is to switch to a shell that *does* support name matching prefixes, like `bash`:
+
+```sh
+#!/bin/bash
+x='test'
+echo "${x^^[t]}"
+```
+
+Alternatively, use external tools like `tr` for case conversion
+
+```sh
+#!/bin/sh
+x='test'
+echo "$x" | tr 't' 'T'
+```
+
+### Rationale:
+
+Case modification in parameter expansion (e.g., `${x^^}`, `${x,,}`, `${x^}`, `${x,[pattern]}`) is a bash and ksh extension. dash and POSIX sh do not support it.
+
+### Exceptions:
+
+If you only intend to target shells that supports this feature, you can change
+the shebang to a shell that guarantees support, or [[ignore]] this warning.
+
+You can use `# shellcheck disable=SC3000-SC4000` to ignore all such compatibility
+warnings.
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!
+* https://github.com/sbaudoin/sonar-shellcheck/blob/master/src/main/scripts/build_checks.yml