update branch names in docs

DEVGUIDE.md

@@ -17,24 +17,24 @@ This will make management of multiple forks and your own work easier over time.
 We recommend the following commands to update your fork:
 
 ```
-git checkout master
+git checkout main
 git clean -xdf
 git fetch upstream
-git rebase upstream/master
+git rebase upstream/main
 git push
 ```
 
 Or more succinctly:
 
 ```
-git checkout master && git clean -xdf && git fetch upstream && git rebase upstream/master && git push
+git checkout main && git clean -xdf && git fetch upstream && git rebase upstream/main && git push
 ```
 
 This will update your fork with the latest from `dotnet/fsharp` on your machine and push those updates to your remote fork.
 
 ## Developing on Windows
 
-Install the latest released [Visual Studio](https://www.visualstudio.com/downloads/), as that is what the `master` branch's tools are synced with. Select the following workloads:
+Install the latest released [Visual Studio](https://www.visualstudio.com/downloads/), as that is what the `main` branch's tools are synced with. Select the following workloads:
 
 * .NET desktop development (also check F# desktop support, as this will install some legacy templates)
 * Visual Studio extension development

INTERNAL.md

@@ -47,8 +47,8 @@ To see all insertions created this way (possibly including for other internal te
 
 ## Less interesting links
 
-[Nightly VSIX (master) uploader](https://dev.azure.com/dnceng/internal/_release?_a=releases&definitionId=70).  Uploads
-a package from every build of `master` to the [Nightly VSIX feed](README.md#using-nightly-releases-in-visual-studio).
+[Nightly VSIX (main) uploader](https://dev.azure.com/dnceng/internal/_release?_a=releases&definitionId=70).  Uploads
+a package from every build of `main` to the [Nightly VSIX feed](README.md#using-nightly-releases-in-visual-studio).
 
 [Nightly VSIX (preview) uploader](https://dev.azure.com/dnceng/internal/_release?_a=releases&definitionId=71).  Uploads
 a package from every build of the branch that corresponds to the current Visual Studio preview to the

README.md

@@ -50,11 +50,11 @@ Even if you find a single-character typo, we're happy to take the change! Althou
 
 | Branch | Status |
 |:------:|:------:|
-|master|[![Build Status](https://dev.azure.com/dnceng/public/_apis/build/status/dotnet/fsharp/fsharp-ci?branchName=master)](https://dev.azure.com/dnceng/public/_build/latest?definitionId=496&branchName=master)|
+|main|[![Build Status](https://dev.azure.com/dnceng/public/_apis/build/status/dotnet/fsharp/fsharp-ci?branchName=main)](https://dev.azure.com/dnceng/public/_build/latest?definitionId=496&branchName=main)|
 
 ## Using nightly releases in Visual Studio
 
-You can use the latest `master` build of the F# compiler and tools for Visual Studio via our nightly releases if you are a Visual Studio user. See details on setup here:
+You can use the latest `main` build of the F# compiler and tools for Visual Studio via our nightly releases if you are a Visual Studio user. See details on setup here:
 
 https://blogs.msdn.microsoft.com/dotnet/2017/03/14/announcing-nightly-releases-for-the-visual-f-tools/
 
@@ -69,22 +69,22 @@ Alternatively, if you _really_ want to live on the bleeding edge, you can set up
 
 These are the branches in use:
 
-* `master`
+* `main`
   - Most contributions go here.
   - Able to be built, installed and used in the latest public Visual Studio release.
   - May contain updated F# features and logic.
   - Used to build nightly VSIX (see above).
   - Gets integrated into https://github.com/fsharp/fsharp to form the basis of Mono releases
   - Gets integrated into https://github.com/fsharp/FSharp.Compiler.Service to form the basis of FSharp.Compiler.Service releases
 
-* `dev15.9`
+* `release/dev15.9`
   - Long-term servicing branch for VS 2017 update 15.9.x. We do not expect to service that release, but if we do, that's where the changes will go.
 
-* `dev16.x`
+* `release/dev16.x`
   - Latest release branch for the particular point release of Visual Studio.
-  - Incorporates features and fixes from master up to a particular branch point, then selective cherry-picks.
+  - Incorporates features and fixes from main up to a particular branch point, then selective cherry-picks.
   - May contain new features that depend on new things or fixes in the corresponding forthcoming Visual Studio release.
-  - Gets integrated back into master once the corresponding Visual Studio release is made.
+  - Gets integrated back into main once the corresponding Visual Studio release is made.
 
 ## F# language and core library evolution