Cheatsheets added

- apk: Alpine Linux package manager
 - gcc: GNU C Compiler
 - grep: Pattern matcher in files or pipes
 - vim: Vi IMproved

cheatsheets/gcc

@@ -0,0 +1,8 @@
+# Compile a file
+gcc file.c
+
+# Compile a file with a custom output
+gcc -o file file.c
+
+# Debug symbols
+gcc -g