[#674] Add a section about the introspective variants in doc

To document what this new variant does
- add a section
- add a description of the variant
- also add an extract from T Deniffel's post to explain what the
  other variants are

variants-doc/tcr_variants.md

@@ -1,7 +1,6 @@
 # TCR Variants
 
-TCR tool can run several variants of TCR, as described in
-[this blog post](https://medium.com/@tdeniffel/tcr-variants-test-commit-revert-bf6bd84b17d3)
+TCR tool can run several variants of TCR, inspired by [this blog post](https://medium.com/@tdeniffel/tcr-variants-test-commit-revert-bf6bd84b17d3)
 by Thomas Deniffel.
 
 We encourage you to read through Thomas's blog post for a deeper understanding of how these
@@ -12,9 +11,10 @@ TCR's tool `--variant` (or `-r`) command-line option.
 
 The variants currently supported by TCR tool are the following:
 
-- The Original
+- The Original (not yet supported)
 - BTCR
 - The Relaxed (default)
+- The introspective
 
 The state diagrams below summarize the behavior of each variant.
 
@@ -28,6 +28,9 @@ tcr --variant=original
 
 ## BTCR - Build && Test && Commit || Revert
 
+> This version tries to build the software first. If it fails, nothing is
+> executed — no commit, no revert. Compilation-Issue solved.
+
 ```shell
 tcr --variant=btcr
 ```
@@ -36,10 +39,26 @@ tcr --variant=btcr
 
 ## The Relaxed
 
+> The second issue of the original suggestion is that your unit-tests get deleted all the time. 
+> The idea is, not to reset the ‘test’ folder but only the ‘src’ folder.
+
 ```shell
 tcr --variant=relaxed
 ```
 
 The above option `--variant=relaxed` may be omitted as this is the default variant.
 
 ![TCR Relaxed variant](../webapp/src/assets/images/variant-relaxed.png)
+
+## The Introspective
+
+This is an extension to the BTCR variant. Instead of simply reverting changes locally, it commits the failing
+changes, and straightaway commits a revert commit to get back to a green state. The goal is to be able to
+retrospect on one's progress through a task. It's useful during deliberate practice sessions, but could also
+serve in day to day coding.
+
+```shell
+tcr --variant=introspective
+```
+
+![TCR Introspective variant](../webapp/src/assets/images/variant-introspective.png)