Merge branch 'sr2021-game-fixes'

Author: PeterJCLaw

images/content/rules/arena-2020.png

@@ -61,7 +61,7 @@ From here in, if you see a `R.something`, the requirement of the `sr.robot` impo
 As well as the attributes listed above, the Robot class also has the following attributes, which you may find useful:
 
 zone
-:    The number of the zone that the robot is associated with.  An integer from 0 to 3 inclusive.
+:    The number of the zone that the robot is associated with. Either `0` or `1`.
 
 mode
 :    Either "comp" or "dev".  When in a competition match, this will be "comp", and at all other times this will be "dev".

programming/sr/index.md

@@ -176,8 +176,7 @@ marker_type
     One of:
 
     * `MARKER_ARENA`
-    * `MARKER_TOKEN_SILVER`
-    * `MARKER_TOKEN_GOLD`
+    <!-- Add other game-specific values here too -->
 
 offset
 :   The offset of the numeric code of the marker from the lowest numbered marker of its type.

programming/sr/vision/index.md

@@ -13,6 +13,19 @@ current competition year are available from the [main rules page][rules-page].
 
 [rules-page]: {{ site.baseurl }}/rules/
 
+[2020](#2020)
+---------------------
+
+<img src="{{ site.baseurl }}/images/content/rules/arena-2020.png" alt="A diagram of the arena for the SR2020 game" class="left" />
+
+The 2020 game, _Two Colours_, challenged teams to score points by retrieving
+coloured tokens from on and around a raised platform in the centre of the arena.
+They had to place these tokens within their scoring zone (i.e. their corner of
+the arena). However, if a team gathered more than one token colour within their
+scoring zone, each token's value would drop from 3 points to 1 point.
+
+Full details of the 2020 game are available in the [rulebook]({{ site.baseurl }}/resources/2020/rulebook.pdf).
+
 [2019](#2019)
 ---------------------
 

rules/archive.md

@@ -1,18 +1,12 @@
 ---
 layout: page
-title: 2020 Rules
+title: 2021 Rules
 ---
 
-2020 Rules
+2021 Rules
 ==========
 
-[<img class="left" src="{{ site.baseurl }}/resources/2020/rulebook.png" />]({{ site.baseurl }}/resources/2020/rulebook.pdf)
-The rules, regulations and specifications for the SR2020 competition can be
-found in the [rulebook]({{ site.baseurl }}/resources/2020/rulebook.pdf).
-
-The PDF may be subject to minor changes, so please ensure you're using the most up-to-date version.
-We will also let you know of any important changes by email.
-
+The rules for SR2021 will be published soon.
 
 Previous Rules
 ==============