Add Contributing to Skia section of docs

site/dev/contrib/cqkeywords.md

+Commit Queue Keywords
+=====================
+
+COMMIT
+------
+
+If you want to test your CL through the commit queue but are not ready to commit 
+the changes yet, you can add the following line to the CL description:
+
+    COMMIT=false
+
+The CQ will run through its list of verifiers (reviewer check, trybots, tree check, 
+presubmit check), and will close the issue instead of committing it.
+
+    CQ_INCLUDE_TRYBOTS
+
+Allows you to add arbitrary trybots to the CQ's list of default trybots. 
+The CQ will block till these tryjobs pass just like the default list of tryjobs.
+
+This is the format of the values of this keyword:
+
+    CQ_INCLUDE_TRYBOTS=master1:bot1,bot2;master2:bot3,bot4
+
+Here are some real world examples:
+
+    CQ_INCLUDE_TRYBOTS=tryserver.chromium:linux_layout_rel
+
+    CQ_INCLUDE_TRYBOTS=tryserver.skia:Build-Ubuntu13.10-GCC4.8-NaCl-Release-Trybot
+
+    CQ_EXCLUDE_TRYBOTS
+
+Allows you to remove trybots from the CQ's list of default trybots. Should only be 
+used when particular builders are failing for reasons unrelated to your code changes.
+
+This is the format of the values of this keyword:
+
+    CQ_EXCLUDE_TRYBOTS=master1:bot1,bot2;master2:bot3,bot4
+
+Here are some real world examples:
+
+    CQ_EXCLUDE_TRYBOTS=tryserver.chromium:win_chromium_compile_dbg
+
+    CQ_EXCLUDE_TRYBOTS=tryserver.skia:Build-Win7-VS2010-x86-Debug-Trybot
+
+    CQ_TRYBOTS
+
+Allows you to list every trybot that you want to run for your CL.
+
+This is the format of the values of this keyword:
+
+    CQ_TRYBOTS=master1:bot1,bot2;master2:bot3,bot4
+
+Here are some real world examples:
+
+    CQ_TRYBOTS=tryserver.chromium:linux_chromium_gn_rel,linux_chromium_chromeos_rel,
+      android_dbg_triggered_tests,android_dbg,mac_chromium_rel,win_chromium_x64_rel
+
+    CQ_TRYBOTS=tryserver.skia:Build-Win7-VS2010-x86-Debug-Trybot,
+      Test-Ubuntu13.10-ShuttleA-NoGPU-x86_64-Debug-Trybot,
+      Build-Ubuntu13.10-GCC4.8-x86_64-Release-Trybot,
+      Build-Ubuntu13.10-Clang-x86_64-Debug-Trybot,Build-Mac10.8-Clang-x86_64-Release-Trybot 
+
+TBR
+---
+
+If you are a Skia committer and cannot wait for a review, 
+then you can include the TBR keyword in your CL's description.
+
+Example:
+
+    TBR=rmistry@google.com
+
+    NOTREECHECKS
+
+If you want to skip the tree status checks, to make the CQ commit a CL even if the tree is closed, 
+you can add the following line to the CL description:
+
+    NOTREECHECKS=true
+
+This is discouraged, since the tree is closed for a reason. However, in rare cases this is acceptable, 
+primarily to fix build breakages (i.e., your CL will help in reopening the tree).
+
+    NOPRESUBMIT
+
+If you want to skip the presubmit checks, add the following line to the CL description:
+
+    NOPRESUBMIT=true
+
+NOTRY
+-----
+
+If you cannot wait for the try job results, you can add the following line to the CL description:
+
+    NOTRY=true
+
+The CQ will then not run any try jobs for your change and will commit the CL as soon as the tree is open, assuming the presubmit check passes.