docs (level 101): fix typos, punctuation, formatting (#160)

* docs: formatted for readability

* docs: rephrased and added punctuation

* docs: fix typos, punctuation, formatting

* docs: fix typo and format

* docs: fix caps and formatting

* docs: fix punctuation and formatting

* docs: capitalized SQL commands, fixed puntuation, formatting

* docs: fix punctuation

* docs: fix punctuation and formatting

* docs: fix caps,punctuation and formatting

* docs: fix links, punctuation, formatting

* docs: fix code block formatting

* docs: fix punctuation, indentation and formatting

courses/level101/metrics_and_monitoring/best_practices.md

@@ -5,35 +5,35 @@
 When setting up monitoring for a service, keep the following best
 practices in mind.
 
--   **Use the right metric type** -- Most of the libraries available
+-   **Use the right metric type**—Most of the libraries available
      today offer various metric types. Choose the appropriate metric
      type for monitoring your system. Following are the types of
      metrics and their purposes.
 
-    -   **Gauge --** *Gauge* is a constant type of metric. After the
+    -   **Gauge**—*Gauge* is a constant type of metric. After the
          metric is initialized, the metric value does not change unless
          you intentionally update it.
 
-    -   **Timer --** *Timer* measures the time taken to complete a
+    -   **Timer**—*Timer* measures the time taken to complete a
          task.
 
-    -   **Counter --** *Counter* counts the number of occurrences of a
+    -   **Counter**—*Counter* counts the number of occurrences of a
          particular event.
 
  For more information about these metric types, see [Data
  Types](https://statsd.readthedocs.io/en/v0.5.0/types.html).
 
--   **Avoid over-monitoring** -- Monitoring can be a significant
-     engineering endeavor***.*** Therefore, be sure not to spend too
+-   **Avoid over-monitoring**—Monitoring can be a significant
+     engineering endeavor. Therefore, be sure not to spend too
      much time and resources on monitoring services, yet make sure all
      important metrics are captured.
 
--   **Prevent alert fatigue** -- Set alerts for metrics that are
+-   **Prevent alert fatigue**—Set alerts for metrics that are
      important and actionable. If you receive too many non-critical
      alerts, you might start ignoring alert notifications over time. As
      a result, critical alerts might get overlooked.
 
--   **Have a runbook for alerts** -- For every alert, make sure you have
+-   **Have a runbook for alerts**—For every alert, make sure you have
      a document explaining what actions and checks need to be performed
      when the alert fires. This enables any engineer on the team to
      handle the alert and take necessary actions, without any help from