findstr: add page (#2336)

pages/windows/findstr.md

@@ -0,0 +1,35 @@
+# findstr
+
+> Find specified text within one or more files.
+
+- Find space-separated string(s) in all files:
+
+`findstr "{{query}}" *`
+
+- Find space-separated string(s) in all files recur[s]ively:
+
+`findstr /s "{{query}}" *`
+
+- Find strings using a case-insensitive search:
+
+`findstr /i "{{query}}" *"`
+
+- Find strings in all files using regular expressions:
+
+`findstr /r "{{expression}}" *`
+
+- Find a literal string (containing spaces) in all text files:
+
+`findstr /c:"{{query}}" *.txt`
+
+- Find only lines that match the query e[x]actly:
+
+`findstr /x "{{query}}" *`
+
+- Display the line number before each matching line:
+
+`findstr /n "{{query}}" *`
+
+- Display only the filenames that contain a match:
+
+`findstr /m "{{query}}" *`