chore: fix case of GitHub (#10928)

diff --git a/dev/committer-instructions.md b/dev/committer-instructions.md
index 029fa7d..5e6524d 100644
--- a/dev/committer-instructions.md
+++ b/dev/committer-instructions.md
@@ -100,7 +100,7 @@
    - [`Area - Cache`](https://github.com/apache/druid/labels/Area%20-%20Cache) - for PRs and issues related to
    Druid's query results cache (local or remote). Don't use for PRs that anyhow relate to caching in different contexts.
    - [`Area - Dev`](https://github.com/apache/druid/labels/Area%20-%20Dev) - for PRs and issues related to the
-   project itself, such as adding developer's docs and checklists, Github issue and PR templates, Github-related issues.
+   project itself, such as adding developer's docs and checklists, GitHub issue and PR templates, GitHub-related issues.
    Don't use for PRs and issues related to CI problems: use either `Area - Testing` for problems with Travis or
    `Area - Automation/Static Analysis` for problems with TeamCity. PRs with `Area - Dev` label should usually change
    files in `dev/` or `.github/` directories.
@@ -158,11 +158,11 @@
 number (such as 0.10.1, while the previous release is 0.10 or 0.10.0), rename the next milestone so that it bumps the
 "minor" number (e. g. 0.10 -> 0.11).
 
-3. Check that the issue addessed in the PR is closed automatically by Github. If it's not, close the issue manually.
+3. Check that the issue addessed in the PR is closed automatically by GitHub. If it's not, close the issue manually.
 
 4. Consider thanking the author for contribution, especially a new contributor.
 
-## Creating a new label on Github
+## Creating a new label on GitHub
 
 After creating a new label for your PR or issue, don't forget to take the following steps:
 
diff --git a/dev/teamcity.md b/dev/teamcity.md
index 0b623a7..39cae3d 100644
--- a/dev/teamcity.md
+++ b/dev/teamcity.md
@@ -19,7 +19,7 @@
   
 ### Overview
 TeamCity is a continuous integration and deployment server responsible for 
-static analysis of Druid source code. Each Github PR request for 
+static analysis of Druid source code. Each GitHub PR request for 
 [Druid](https://teamcity.jetbrains.com/project.html?projectId=OpenSourceProjects_Druid) 
 is checked by TeamCity automatically.
 
@@ -29,12 +29,12 @@
 ### Becoming a Project Administrator
 Druid committers shall obtain a status of a [Druid project](
 https://teamcity.jetbrains.com/project.html?projectId=OpenSourceProjects_Druid)
-administrator. First, the Druid committer needs to log in teamcity.jetbrains.com using their Github account.
+administrator. First, the Druid committer needs to log in teamcity.jetbrains.com using their GitHub account.
 Then, somebody who is already a project administrator needs to do the following:
 
  1. Follow the "Administration" link in the top-right corner of the page
  2. Follow the "Users" link in the "User Management" section in the menu on the left
- 3. Type the committer's Github handle in the "Find users" text input, press "Filter"
+ 3. Type the committer's GitHub handle in the "Find users" text input, press "Filter"
  4. Select the committer
  5. Press the "Assign roles" button in the bottom of the page
  6. Select "Role: Project administrator" and "Scope: Open-source project -> Druid" in the inputs, press "Assign"
diff --git a/extensions-contrib/moving-average-query/README.md b/extensions-contrib/moving-average-query/README.md
index 918f175..e0ecffc 100644
--- a/extensions-contrib/moving-average-query/README.md
+++ b/extensions-contrib/moving-average-query/README.md
@@ -26,4 +26,4 @@
 
 Documentation 
 =============
-See the druid.apache.org website or under [Druid Github Repo](https://github.com/apache/druid/tree/master/docs/development/extensions-contrib/moving-average-query.md).
+See the druid.apache.org website or under [Druid GitHub Repo](https://github.com/apache/druid/tree/master/docs/development/extensions-contrib/moving-average-query.md).