Added Caveats of the current plugin version

Change-Id: I22ab59873c5f5e323c413a2407aaad97419f98e1

src/main/resources/Documentation/config.md

diff --git a/src/main/resources/Documentation/config.md b/src/main/resources/Documentation/config.md
index c2fa1f1..1de3fbd 100644
--- a/src/main/resources/Documentation/config.md
+++ b/src/main/resources/Documentation/config.md
@@ -66,4 +66,13 @@
     ignore-file-suffix = .ko
     ignore-file-suffix = .png
     ignore-file-suffix = .exe
-  ```
\ No newline at end of file
+  ```
+
+# Caveats
+
+* Extracting branches and hashtags is a really expensive operation. At the
+moment the plugin works for "small" repositories (~50K commits). With bigger
+repositories the plugin might cause OOM.
+
+* It is not possible to extract data about a single commit, but only aggregations
+of them.
\ No newline at end of file