llvm-ar, llvm-nm, llvm-strings: add page (#6566)

pages/common/llvm-ar.md

@@ -0,0 +1,7 @@
+# llvm-ar
+
+> This command is an alias of `ar`.
+
+- View documentation for the original command:
+
+`tldr ar`

pages/common/llvm-nm.md

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+# llvm-nm
+
+> This command is an alias of `nm`.
+
+- View documentation for the original command:
+
+`tldr nm`

pages/common/llvm-strings.md

@@ -0,0 +1,7 @@
+# llvm-strings
+
+> This command is an alias of `strings`.
+
+- View documentation for the original command:
+
+`tldr strings`