added 3 more snippets

Author: majvax

snippets/regex/miscellaneous/ipv4.md

@@ -0,0 +1,17 @@
+---
+Title: IPv4
+Description: Matches IPv4 address
+Author: majvax
+Tags: ipv4,networking
+---
+
+
+```regex
+^((25[0-5]|2[0-4]\d|1\d{2}|\d{1,2})\.){3}(25[0-5]|2[0-4]\d|1\d{2}|\d{1,2})$
+
+
+-> Usage:
+123.300.0.101 ✗
+127.0.0.1 ✓
+192.168.0.1 ✓
+```

snippets/regex/miscellaneous/unintentional-duplication.md

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+---
+Title: Unintentional Duplication
+Description: Matches duplicated word in a text.
+Author: majvax
+Tags: trim
+---
+
+
+```regex
+\b(\w+)\s+\1\b
+
+
+-> Usage:
+I need to finish this task ✗
+I need to to finish this task ✓
+```

snippets/regex/miscellaneous/whitespace-trimmer.md

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+---
+Title: Whitespace Trimmer
+Description: Matches leading and/or trailing whitespace.
+Author: majvax
+Tags: trim
+---
+
+
+```regex
+^\s+|\s+$
+
+
+-> Usage:
+(don't account for the quotation marks, it just to visualize whitespace)
+"Hello World" ✗
+" Hello World" ✓
+"Hello World " ✓
+" Hello World " ✓
+```