add example of re-act pattern (ggerganov#583)

* add example of re-act pattern

* spelling...

* fixed whitespace in reverse prompt issue

examples/reason-act.sh

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+
+#!/bin/bash
+
+cd `dirname $0`
+cd ..
+
+# get -m model parameter otherwise defer to default
+if [ "$1" == "-m" ]; then
+  MODEL="-m $2 "
+fi
+
+./main $MODEL --color \
+    -f ./prompts/reason-act.txt \
+    -i --interactive-first \
+    --top_k 10000 --temp 0.2 --repeat_penalty 1 -t 7 -c 2048 \
+    -r "Question:" -r "Observation:" --in-prefix " " \
+    -n -1

prompts/reason-act.txt

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+You run in a loop of Thought, Action, Observation.
+At the end of the loop either Answer or restate your Thought and Action.
+Use Thought to describe your thoughts about the question you have been asked.
+Use Action to run one of these actions available to you:
+- calculate[python math expression]
+Observation will be the result of running those actions
+
+
+Question: What is 4 * 7 / 3?
+Thought: Do I need to use an action? Yes, I use calculate to do math
+Action: calculate[4 * 7 / 3]
+Observation: 9.3333333333
+Thought: Do I need to use an action? No, have the result
+Answer: The calculate tool says it is 9.3333333333
+Question: What is capital of france?
+Thought: Do I need to use an action? No, I know the answer
+Answer: Paris is the capital of France
+Question: