Add Increment All The Numbers as a vim til.

vim/increment-all-the-numbers.md

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+# Increment All The Numbers
+
+Vim's substitution feature can be used for more than simple static text
+replacement. Each replacement can be the result of some operation on the
+original text. For instance, what if we'd like to increment all numbers in the
+buffer? We can achieve this by searching for all numbers and then using `\=`
+with `submatch`. Whenever the replacement string of a substitution starts
+with `\=`, the remainder of the string is evaluated as an expression.
+
+Given the following text in our buffer:
+
+```
+1 2 a b c 45 123 1982
+```
+
+We can run the following substitution command:
+
+```
+:%s/\d\+/\=submatch(0)+1/g
+```
+
+This will transform all digits in the buffer resulting in:
+
+```
+2 3 a b c 46 124 1983
+```
+
+Want to decrement all the numbers instead?
+
+```
+:%s/\d\+/\=submatch(0)-1/g
+```
+
+See `:h sub-replace-expression` for more details.