Fix spelling typos

modules/gapi/doc/00-root.markdown

@@ -95,7 +95,7 @@ Internally, cv::GComputation::apply() compiles the captured graph for
 the given input parameters and executes the compiled graph on data
 immediately.
 
-There is a number important concepts can be outlines with this examle:
+There is a number important concepts can be outlines with this example:
 * Graph declaration and graph execution are distinct steps;
 * Graph is built implicitly from a sequence of G-API expressions;
 * G-API supports function-like calls -- e.g. cv::gapi::resize(), and

modules/gapi/doc/01-background.markdown

@@ -36,7 +36,7 @@ software optimization due to diffent costs of memory access on modern
 computer architectures -- the more data is reused in the first level
 cache, the more efficient pipeline is.
 
-Definitely the aforementioned techinques can be applied manually --
+Definitely the aforementioned techniques can be applied manually --
 but it requires extra skills and knowledge of the target platform and
 the algorithm implementation changes irrevocably -- becoming more
 specific, less flexible, and harder to extend and maintain.

modules/gapi/doc/slides/gapi_overview.org

@@ -242,7 +242,7 @@ Graph *protocol* defines what arguments a computation was defined on
 - A type name (every operation is a C++ type);
 - Operation signature (similar to ~std::function<>~);
 - Operation identifier (a string);
-- Metadata callback -- desribe what is the output value format(s),
+- Metadata callback -- describe what is the output value format(s),
   given the input and arguments.
 - Use ~OpType::on(...)~ to use a new kernel ~OpType~ to construct graphs.
 #+LaTeX: {\footnotesize