Fix a few typos in site *.md documents

Fix several typos in site *.md documents.

Touched documents listed:

• hadoop-tools/hadoop-archives/src/site/markdown/HadoopArchives.md.vm
• hadoop-common-project/hadoop-common/src/site/markdown/filesystem/testing.md
• hadoop-common-project/hadoop-common/src/site/markdown/filesystem/fsdatainputstream.md
• hadoop-common-project/hadoop-common/src/site/markdown/filesystem/filesystem.md
• hadoop-common-project/hadoop-common/src/site/markdown/filesystem/notation.md
• hadoop-common-project/hadoop-common/src/site/markdown/filesystem/introduction.md
• hadoop-common-project/hadoop-common/src/site/markdown/filesystem/model.md
• hadoop-common-project/hadoop-common/src/site/markdown/InterfaceClassification.md
• hadoop-common-project/hadoop-common/src/site/markdown/ClusterSetup.md
• hadoop-common-project/hadoop-common/src/site/markdown/Compatibility.md